Unless the closest store is too far away...I'd actually go to the store to use the gift card. I wouldn't want to use any of it towards shipping charges. Plus since you mention clothes...there is usually a much better selection in the store.
Things we get at Petsmart ~
Hair gel, shampoos and conditioners, toothpaste, nylon harnesses, leashes, personalized dog tags, toys, and bully sticks.
Actually if I had a gift card...it would be applied toward the cost of clippers. That's my next petsmart purchase.