Years ago, when restaurant bills were settled with cash more frequently than anything else, tipping odd amounts was the norm. Customers would round up the bill to something that's easy to pay, e.g., two $20 notes for a bill of $34.53, and leave the change.

My mother worked as a waitress when I was young. She complained about lots of things every night when she came home but never about the customers who left her $5.47 instead of a "round" $5. Yes, she brought home a lot of coins, but so what. She'd throw them in a jar in the kitchen. We kids would take the quarters and dimes to pay for school lunches. The nickels and pennies we'd have a party to roll up every so often and see if there was enough money there to do something fun like buy ice cream.