I know you’re bad at math. You didn’t work hard enough at math when you were a kid. That’s fine. I’m here to save you from an easy faux pas: not knowing how to tip.
First, look at the bill. Say you just ate at a cheap sit-down establishment with someone special (but obviously at the point in the relationship where you don’t have to impress anyone). The bill is $31.88, and you don’t know what to do.
Don’t just round up to the next five-dollar increment.
Do this instead. Move the decimal point one point to the left. Now hold the $3.188 in your head.
Double that number. Here the new number is $6.376. That’s 20%. Add that to the bill and you pay $38.256.
Addition too hard at any point? Round. But remember, round up. 3.188 can become 3.50 or 4.00. Double that to 7 or 8. Then addition should be easier (ie, $38.88 or $39.88).
Like round numbers? Keep rounding up. Boom. Easy.
This is your baseline. You don’t tip below this. If you can afford to go out, you can tip the person who is your temporary servant. It can be thankless degrading work, and the government says that all you have to pay these people is $2.13 or something horribly insulting.
I know, I’ve been there. I’m not there anymore but people I love have to deal with it on a daily basis.
Don’t be an asshole. Tip your waiters.