Many businesses added specific surcharges to final sales to offset the tariffs they paid. While they have no legal obligation to refund those surcharges they imposed, it would be straightforward to do so and it would be the right thing to do.
Or keep it as a rainy day fund against the next time one of their major markets goes insane with attempted extortion, possibly successfully next time? Their customers paid a price they were comfortable with —- if a company returns part of that to the customer, they disadvantage themselves compared to their competitors who do not do so in the next round of tariffs, since their competitors can use the rainy day fund to delay price rises, capturing customer spend (which is to say, competitor-voluntary-donation-to-customer spend).
Or keep it as a rainy day fund against the next time one of their major markets goes insane with attempted extortion, possibly successfully next time? Their customers paid a price they were comfortable with —- if a company returns part of that to the customer, they disadvantage themselves compared to their competitors who do not do so in the next round of tariffs, since their competitors can use the rainy day fund to delay price rises, capturing customer spend (which is to say, competitor-voluntary-donation-to-customer spend).