I called BS on the 15% tip rule in my head, then I did the math on a $62 diner bill in Boise
I always thought the whole 'double the tax to get the tip' trick was just something servers made up so people would leave more. Then a buddy and I ate at a diner in Boise and the bill came to $62 and change, and I sat there trying to do 20% in my head while everyone stared at me. He goes, just double the tax, and the tax was $3.72, so we tipped $7.44, which was way less than 20% and honestly felt a little cheap. I did the real math later and doubling the tax only hits about 12% in that city, so the trick quietly shortchanges servers where the sales tax is low. My mom swears by it though, says it's close enough, and now I don't know if I've been overtipping or undertipping for a decade. So what's the actual rule people use, flat 20%, the tax trick, or just punching numbers until it feels right?
Watched my stepdad do the tax trick for years and he always rounded up to the next dollar, so on a $62 bill he would've tipped like $8 and felt great about it. The thing is, that trick only works in cities where the sales tax is high, so in Boise you're basically shorting the server every single time without knowing it. Honestly I just do 20% and round up now, because doing math at the table while people stare at you is the worst part of eating out.