Back in the day, the trick was when you owe the customer, say, 78 cents, you short them a quarter and only give them 53 cents. You still take that quarter out of the till, you just hold it with your pinkie so the cameras cant see it while you hand the rest of the change to the customer. If they notice they got shorted, you just say "oh sorry" and reopen the till to hand them the quarter thats still in your pinkie. But if they dont notice, you just made a quarter. This relies on you being able to memorise who youve shorted and not short the same person multiple times without a long time in between, because then people start to get sus