Apparently you can use $15 codes for membership, but can you use $20, $10, and $5 (more than one 10 and 5)?
As far as I know, most of the $15 cards are also labled as "game cards" and those that are not labled as game cards can't be used to pay for a sub. I know the last ones I bought specifically have 1500 SC or 30-day Game Card printed on the front in big font.
