how to get cash back from a gift card

The mango lemonade we bought yesterday doesn't taste like lemonade!  Ming said it tastes like mango soda.  Without the carbonation, I said.  The weird thing is that the strawberry lemonade definitely tastes like lemonade.  So we pondered the difference.  Ming said something about opaqueness, and I said something about cause vs effect.  We didn't make much progress.  But it was on sale, so the sign said, but then it rang up as full price, so then we got refunded $2.99 in cash.  And that's how you get cash back from a gift card.