The little things can be a big adjustment when changing countries. One of the things that I had forgotten how to do while I was back home was tipping at restaurants and bars. Taxes are another thing that also has to be considered while shopping in different countries.
Tipping in Taiwan isn't really something you have to do math for. At little noodle shops or food vendors along the alleyways, tipping isn't done at all. For cafes and other sit down restaurants usually a 10% service is added to your bill. It's a bit more convenient when it comes to totaling up how much everyone owes. You might try to leave an additional tip, but the waitstaff will usually think you forgot your change and chase after you to return it, since this isn't a normal occurrence. Bars here usually do have a tip jar, but it's more common at Western establishments.
When shopping, the price you see on the tag is the price you pay. There's no additional taxes added on to it once you get to the register. So it's easy to get your money ready while you're in line.
Tipping in America can get a bit more complex. There's deciding how happy you were with the service, then attaching a percentage to it. 15%, 20%, 25%.... if you have a big party then there's dividing up the bill, then adding a tip to it. It's inconvenient when it comes down to it, too much math. The one thing that I do like about it, is if you were really unhappy with the service you're able to show it in your tip, unlike having to pay the 10% service charge.
After living abroad for a while, shopping confuses me, especially when it's smaller items that I plan to pay cash for. I'll have my money ready when I get to the counter, but I forget that sales tax is added AFTER the item is rung up. Suddenly I have to dig through my wallet for the additional 5%-5.5% tax that is added in Wisconsin. It can be a little embarrassing especially when there's a line behind me.
Taxes...always getting the better of me!