you would need to prove what part of the amounts you paid were due to tariffs, and which were ordinary price changes. All vendors would need to publish that information, and be honest about it. Don't see it coming.

The real thing is, price changes tend to be proportional to tariffs. If the tariff was $20, the consumer got charged $40 more. But not uniformly -- every price is different, there are other non-tariff price changes too, prices can increase before or after tariffs not exactly at the same time, etc.

If companies want to try to refund customers and come up with their own formulas for that, that's great. But usually there isn't some objective right answer that can be imposed externally.