If you want to get into a heated discussion, gather a group of your friends together and ask them about when and who you should tip.

Whether you hate it or don't mind it, tipping is a part of life in the U.S. It can also be an added stress when you're not sure whether to tip -- especially around the holidays.

The cost of tipping is often overlooked in household budgets and can take quite a bit of money out of your bank account over time. Conversely, if you happen to work in a job that relies on tips, that money can be a significant portion of your overall pay.

According to a recent

PayScale.com

study on tipping, pizza delivery drivers receive 36% of their overall wages from tips. Bartenders count on tips for 47% of their take-home pay. And waiters/waitresses depend on tips for 61% of their wages. How you ultimately decide to tip can have a great effect not only on how much you spend, but on a person's income for that day.

"For jobs where tipping is common and a high fraction of the wages, like waiters and gaming table dealers, tips are not 'bonuses'. Tips turn a minimum wage job into a living wage," says Dr. Al Lee,

PayScale.com

's director of quantitative analysis. "The personpaying the tip provides more of the employee's income than the official employer."

"For jobs where tips are reported very frequently, it is social convention to tip," Lee continues. "Even when the tip is not a large fraction of income, such as with a dog groomer or massage therapist, the tip is still significant. How many people do you know who would happily take an 8% pay cut?"

Here are five simple steps to help form your own tipping rules so that you're comfortable with this practice:

1. To tip or not to tip

: While tipping is customary, it is not required (although you will find that in certain situations, a gratuity will sometimes be automatically added to your bill, as the case for a large party of people at a restaurant). It's your choice whether to leave a tip. If you feel strongly against tipping, you have every right not to tip at all.

For most people, however, it won't be an all-or-nothing question, but a question of when to tip and when not to. Most people will tip at a sit-down restaurant, but do you tip the babysitter? How about the mailman and garbage collector? How about leaving money in the tip jar on the coffee shop counter? Deciding ahead of time when you are willing to tip and when you aren't can eliminate a lot of the stress.

2. Set comfortable guidelines

: A standard tip for a restaurant meal is 15% to 20%. If you receive average service, will you leave a 15% or a 20% tip? Many people leave a 10% tip for poor service, 15% or 20% for good service and even more for outstanding service. Having a formula that you know and feel comfortable with ahead of time will make the tipping portion of the night much easier and less of a hassle.

3. What's the base?

: It is customary to tip on the normal price of the food, goods or service that you are receiving. This can become an issue if you have a coupon or gift certificate, which brings the price you pay well below what the normal price of the goods or service. It is also customary to tip on the pre-tax total, rather than total amount of the bill.

4. How you figure?

: One of the most difficult aspects of tipping for many people is calculating the correct amount. One way, if you live in a state which has a state sales tax, is to use the tax to help you figure out the tip. For example, if the sales tax rate is 4%, you can multiply the tax on the bill by 4 to give 16% or by 5 to give a 20% tip.

Another simple way is to take 10% of the bill and then double it, if you want to leave 20%. If your math isn't up to par, getting a tip card and placing it in your purse or wallet can save a lot of anxiety.

5. Holiday tipping

: The holidays can be hard on tippers. The season comes once a year, and many people are unsure whom they need to tip. A rule of thumb is that you should consider tipping those who have served you or your family during the year and with whom you have developed a personal relationship.

According to a

Consumer Reports

survey, people give holiday tips to a wide variety of people, including child care providers, housekeepers/cleaners, children's teachers, hairdressers, newspaper carriers, manicurists/pedicurists, barbers, gardeners/lawn-care crews, mail carriers, school-bus drivers, apartment building caretakers, fitness trainer/instructors and sanitation/recycling collectors.

Once you have formed tipping guidelines for yourself, you should feel much more confident and comfortable when tipping people. You'll know that your tips are directed the way that you want them to be rather than through spur-of-the-moment decisions.

Jeffrey Strain has been a freelance personal finance writer for the past 10 years helping people save money and get their finances in order. He currently owns and runs SavingAdvice.com.