The local tesco has a couple of conveyor belt help yourself tills. But if your shopping backs up past a certain point you have to stop and bag some so you can scan more. While bagging some some stupid kids walk up and start scanning their sweets, realise with help what they are doing and wander off. Assistant comes over and says they can only cancel the last item so have to go get the other stuff to scan the barcode to take it off. While they do that I get bored, leave the lot and go to asda.