You don't calculate change. You just count it out, picking up coins and bills as you go. Start at the sum to pay and count towards the amount the customer gave you. Work your way up from the least significant digit using the smallest denominations. No hard mental calculations are involved, you just need to know how to count. Basic cashier knowledge they should be teaching you on day one.
"Basic cashier knowledge they should be teaching you on day one."
About 10ish years ago I had an idea for a product that would essentially provide online training on this for cashiers. Back then I thought 'but everything is moving to cashless payments, plus more and more registers calculate change, no need for this". I wonder sometimes if this was The One That Got Away for me...
