>
>1) Scan can of tomatoes
>
>2) Drop a CD in bag
>
>3) Scan tomatoes again
>
>4) Drop tomatoes in bag
>
>I don't think it has a database relating SKUs and weight.
>
>Any knowledge or guesses?

We have them here at Meijer's.

The PLU system knows the weight as well as price, for every item with a UPC.
There's also a TV camera that does a frame grab when you scan an item.
There's also someone watching. :)

It's not foolproof, but it's good enough. Theoretically, you could put a barcode from item X that weighs 1 lb but costs $1 on item Y that costs $50 and weighs 1 lb, but I think they would notice.

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