There are varying implementations. Stop and Shop supermarkets have Symbol guns running Windows CE, and an iOS/Android app. You scan as you shop. When you get

There are varying implementations. Stop and Shop supermarkets have Symbol guns running Windows CE, and an iOS/Android app. You scan as you shop. When you get to a register you scan the "End Order" barcode on the register, then scan your Stop & Shop card. That's it. Pay. They even recently revved their software to speed up the process and reduce processing delays. I can check out an entire cart in about 40 seconds, and everything is already bagged the way I want it.