Ultimate Game Card issue

I live in Canada and I bought a $20 ultimate game card yesterday from my nearby 7-eleven and it's ready for use, and so I typed it in on pay by cash for some game and it says I still owed $0.93 CAD due to the currency change ($20.93 CAD).

I don't know what to do since the only way to pay $0.93 CAD extra is to buy another $20 ultimate game card.

Please help :S.

Edit: Since there's no way to fix this, I am buying a US Ultimate Game card in trade for $2+ we can negotiate the price

 

Bumpu