Most people are bad tippers
I just read an article called How to Avoid Accidental Overtipping, at 2 Pennies Earned. The gist of the article is that you should tip based on the subtotal, and not the after-tax total. You may be tipping $1-$2 too much ( !! ) every time you eat out.
If you’re obsessing over $1 when you’re eating out, then guess what - you can’t afford to eat out! Servers work hard and put up with a lot of crap from ungrateful, rude customers. Tip well, and don’t fret over a buck or two. Your server needs it more than you do.