It’s not really fraud threats, but the fact that it “empties” your cash drawer. If someone is given change for $100 minus their order, you now have up to 4 less

It’s not really fraud threats, but the fact that it “empties” your cash drawer. If someone is given change for $100 minus their order, you now have up to 4 less $20s, and a $100 that can only be gotten rid of through exchanging between tills/cash box or someone asking for $100 cash back.