That's a thing only if you don't emit receipts or use a modern POS system. In particular it would happen in flee markets or in old shops that only keep a very forgiving paper trail.

But otherwise your POS won't let you get away with that, and your customers will usually be grossed if you're handing them goods for cash without any receipts. Food business could be the last bastion where it would somewhat work on a regular basis IMHO.