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theirs is the best so far.One of my local Circle Ks installed a couple of new self-checkout machines, and they are pretty awesome. You walk up to them with your handful of items, and set the items on the table. A camera identifies everything you have and adds it all up. Swipe your card, and head out. No scanning.
I'm not sure if the camera identifies everything, or if all their stuff has RFID tags.
we use RFID where I work and it works great.