Another way to keep an eye on your employees is to use an exception-based reporting system at your point of sale, says Doyle. He says that the systems will flag possible fraudulent transactions, such as excessive refunds or voids, and excessive refunds or voids outside of store hours. Review video daily and POS several times a week to determine if there are any issues that you need to look into further. Limit the access to your surveillance systems to as few people as possible to avoid tampering.