Yes, not only have I seen people do this all the time. Not only that, I've also seen stores allow it all the time.
As a matter of fact, my girl has bought detergent from the store, didn't like it (opened!) and returned it, was given credit on a gift card, gave the gift card to someone else who then bought something from the store. In one case they gave her the $0.96 back in cash instead of leaving it on the card.
Bitcoin Dr