This is a terrible idea. That means no discounts for people in need, and no doctors saying "don't charge her for that aspirin" as both would become illegal.
I'm all for transparency in pricing, but the lack of flexibility in charging customers is already a big problem. When you go to the hospital, everything is charged at max-price, then insurance companies pay out their negotiated rates. People without insurance don't have the ability to negotiate and end up with ludicrous bills that even the most generous insurance company wouldn't pay.