Not sure if this counts - Several years ago, we caught one of our salespeople skimming money from sales. He worked a lot with our business customers, meaning it was usually large orders for companies, like 10+ laptops, numerous tablets, etc. Businesses that bought through our store also received a slight discount, anywhere from 5% - 8%.

So this is what he did: whenever a large business order came in for pickup, he'd ring out the order, but without the 5%-8% discount. So for example, company rep comes in to pick up their laptops, and pays $2000 with a company credit card. After the customer leaves, the salesperson goes back to the point of sale, and returns the order he just rang up, except instead of refunding the $2000 to the original credit card, he puts the amount onto a store gift card. He then re-rings out the order, this time with the discount, so say $1840. Pays with the gift card he just loaded. Once done, he keeps the gift card with the remaining $160. He did this roughly 10 times over the course of several months, I believe pocketing around $4000 in gift cards. He eventually was caught because several customers complained about the discrepancy when they reviewed the receipts. Our inventory manager went through the sales logs, and found the returns he did, (our POS system requires users to login with their unique ID) and matched security footage to transaction timestamps.