Just do all retailers, for supermarkets it is easy to implement, many publish the prices already. The customer ends up paying for the implementation anyway therefore the question should be if the customer is interested enough in this "new" product. I cant imagine someone poor enough to not want to know where to shop?
OT I would take it much further: I want government to process all transactions and do VAT automatically. You upload the price of your jar of peanut butter, you upload my order of 10 jars, I pay though the government portal, the amount after taxes is deposited into the store's bank account.
Then we could do lame things like ration peoples liquor, the amount of weed they buy, increase the price of your 15th quarter pounder this week but also prevent people from buying all the toilet paper in all the stores. (why have such a convenient mechanism for foreign agents to turn a country into chaos?)
Besides getting rid of the slow, complicated, bureaucratic, expensive administrative burden of taxation and the fines that come with it it would enable very lame things many would oppose and they would be right to do so. That is, until rationing is needed for some reason. Then you have a robust system in place to do it.
I mean, I can easily buy all of the canned food from my local stores. Why would I leave any for you? I'm sure people would prefer it that way. When a real crisis arrives you'd really want to be spending your time on preventable side effects.