We say in America that only two things in life are unavoidable: death and taxes.Most cities and/or states in the US collect a sales tax on almost everything you buy. When you move into a new community, it is a good idea to ask how much the local sales tax is, and what items are and are not taxable. Both taxable items and the amount of tax vary considerably from place to place, from one or two percent in some places up to eight or ten in others. The New York City sales tax, for example, is currently 8%, so if you buy a pair of ＄ 40 shoes you will actually have to pay ＄ 43.20. This makes paying and getting correct change much more difficult.Another thing that makes service exchanges more complicated is tipping. Waiters and waitresses, cab drivers, barkers and all sorts of other people must be tipped in most places. Their employers give them low wages because it is expected that customers will make up the difference. If you don’t, the service person can’t earn a living. Tipping also varies from place, generally in the area of 15% of your bill (before taxes), but again you should ask local residents whom to tip and how much. Why do American people have to tip for many of the services they receiveBecause service-sector employees are typically given（）