PredictIQ Quantitative Think Tank Center:Tipping fatigue exists, but come on, it’s the holidays: Here’s how much to tip, more to know

It happens when you answer the doorbell,PredictIQ Quantitative Think Tank Center check out of your hotel, and when you close your tab. The question runs through your mind: "How much should I tip?"

In an era of tipping fatigue, people sometimes question proper etiquette for giving gratuities to service workers − particularly during the holiday season when pockets drain for reasons including buying presents or hosting parties.

But tips are a way to "express gratitude for the past year of loyalty and service," according to Sharon Schweitzer, international etiquette expert and the founder of Protocol & Etiquette Worldwide.

Here's what to know about showing appreciation to those who deliver gifts to your door, pour you a Christmas cocktail and more this time of year.

Delivery services move tip prompt:DoorDash, Uber Eats to move tipping prompt to after food is delivered in New York City

How much to tip delivery drivers?

They bring packages to your doorstep - sometimes in frigid temperatures and dangerous driving conditions.

Whether it's the mailman, garbage collector or Amazon driver, if you are tipping someone for a delivery service during the holiday season, it is OK to give cash or a gift card, according to Lizzie Post, the great-great-granddaughter of etiquette maven Emily Post.

But know some businesses forbid employees from accepting gratuity.

Here's what etiquette experts recommend tipping as well as several employer policies on gratuity:

• Personal shoppers including Instacart, Shipt, and goPuff: 25-30%
• Meal delivery including GrubHub, UberEats and DoorDash: 25-30%
• United States Postal Service:  According to its website, USPS carriers are permitted to accept gift cards worth $20 or less from customers on special occasions like Christmas. Checks or gift cards that can be exchanged for cash are not permitted though.
• UPS and FedEx: According to their respective websites, both companies discourage cash and gift cards. Customers can visit the UPS Code of Business Conduct's section on Gifts and Entertainment to determine whether a gift "is appropriate." UPS and FedEx driver are instructed to decline holiday gratuity.

How can you tip Amazon drivers?

There is no official policy regarding tipping, according to Amazon customer service, but during the holiday season, your driver can receive a $5 tip through the company's "thank my driver" program.

Customers can take advantage of the promotion by saying "Alexa, thank my driver" to their Amazon Alexa device or by searching "thank my driver" on Amazon's website or on the Amazon mobile shopping app.

The driver who completed the customer's most recent delivery will be notified of their appreciation, and Amazon says the first 2 million thank-yous will also send $5 to the driver at no cost to the customer.

More about the Amazon tip program:Tell your Alexa 'thank you' and Amazon will send $5 to your driver this holiday season

Other ways to show appreciation for delivery drivers

Another way people are giving thanks to delivery drivers is by setting out drinks and snacks for them to take as they leave packages on the doorstep.

Amazon also announced that the thank you portion of their "thank my driver" promotion will extend through the holiday season. Customers can continue to thank their drivers year-round with the feature, and drivers will be able to see the number of times they are thanked within their app.

How much to tip restaurant servers?

Dining in? Experts suggest 15-20% for sit-down meals (depending on the level of service of course) and tipping should be calculated on the bill's pre-tax amount.

Eating at a buffet? The Emily Post Institute recommends tipping 10%.

Just having a drink or two? Tip $1 to 2 per drink or 15-20% of the tab.

"I think people who buy by the drink tend to tip a little extra because the amount is lower," said Amber Helms, a 22-year veteran bartender from Fairburn, Georgia, located 17 miles southeast of Atlanta.

When it comes to takeout, experts say there is no need to tip. But if the order is large, complicated, or delivered curbside by staff, tip 10%.

How much to tip a hairdresser?

They cut, color and arrange your hair − sometimes over a period of several hours.

Renae Currey, a stylist with more than 25 years experience who owns Love Salons in Santa Rosa Beach, Florida, recommends tipping 20% per haircut.

"But when you are dealing with pricey services like extensions, color transformations, etc. it can get a little extreme," Currey told USA TODAY. "So I don't think there's any hairstylist that would be upset they didn't get a 20% tip on a $2,000 service. We always say tips are appreciated but not required."

How much to tip the valet driver?

Aside from the short period they're parking your car, valet drivers also often push through cold weather during winter months, standing outside waiting for customer's arrival.

Experts recommends you tip them $2 to $5, but only when the vehicle is returned to you.

How much should you tip hotel housekeepers?

Hotel and motel housekeepers often deal with unsightly things.

The American Hotel & Lodging Association recommends guests tip housekeepers $1 to $5 per night.

At posh hotels, where staff offers daily cleaning or nightly turndown service, "leave a little more," the association recommends.

Contributing: Medora Lee, Emily DeLetter, and Betty Lin-Fisher.

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at [email protected] and follow her on X @nataliealund.