Let's say something was 20¢. You could pay with 2 dimes or 4 nickels or 5 three cent pieces and a nickel. Pay with a quarter and get a nickel back. Forms that require 2 or 4 cent in change you would just have to use extra coin to get the right change back. It's not perfect, but it keeps the government hands out of it. Besides, we had these before in our history, they were honestly just too small!