I think it's more fun to just pull out your wad of bills and cavalierly round up to the next dollar. Your enjoyment may be spoiled in situations where the customer is too math challenged to understand what you did.
I have never tipped a pizza delivery man less than a deuce, and my orders are almost always small. I think I have had pizza delivered about four times in my 64+ years. I would hate to work with a bunch of jerks like them.