Last night I placed 2 TRU orders and saved $10 each time using Google checkout. I just signed up a different credit card and got the $10 sign-up promotion, too. However, you're not able to combine promotions when checking out. If the amount of the purchase is over $30 Google automatically applies it's current $10 off of $30 promotion. If it's under $30 it applies the $10 for signing up promo instead.