I've heard of these, but never seen them in use (Quebec). Probably due to risks, as local law says (when using barcodes, without prices on each prooduct):
Rules of the Accurate Pricing Policy
If the pricing error involves a product that costs $10 or less, the product is given to the customer free of charge.
If the pricing error involves a product that costs more than $10, the merchant must sell the item at the advertised price and give the consumer a $10 discount.
If the same pricing error occurs for identical products during the same transaction, the merchant must sell each product at the advertised price, but the $10 discount only applies to one product.
Mistaken updates, or hacking, could be quite costly. Maybe this risk is just perception, but...
Rules of the Accurate Pricing Policy If the pricing error involves a product that costs $10 or less, the product is given to the customer free of charge.
If the pricing error involves a product that costs more than $10, the merchant must sell the item at the advertised price and give the consumer a $10 discount.
If the same pricing error occurs for identical products during the same transaction, the merchant must sell each product at the advertised price, but the $10 discount only applies to one product.
Mistaken updates, or hacking, could be quite costly. Maybe this risk is just perception, but...