They give candy for change, they make a mint!

In Bolivia, it is the responsibility of the customer to have the exact change. If you don't, they round-up the amount you owe at the cash register to the next 50 centavos and then give candies for change, or no change at all. They do this in grocery stores all day, everyday to every customer ... they make a mint by shortchanging!

To beat them at their own game, I do the math in my head or on a calculator as I make my selections so that the bill will be exact. For example, I select a specific package of meat or cheese to make the final bill an even amount.