Whatever 4% of the cards total value would be. If its $100 then I charge 4% so it would be $104. They are no tax on gift cards. But they are prepaid debit cards such as Greendot, Vanilla, and Amex. They would be a additional cost to activate the card at the store, usually from what I've seen on most visa and mastercards is 2.95
But the rates do vary from card to card. I don't know why but they do. Basically all your doing is paying me to walk to the gas station and get a card for you. I live beside a Shell, Thortons, and Speedway all within 10minutes there and back *if the line isn't long*.  Escrow is always welcomed and offered.