Source for "bonus" money on gift card

[Jason]

In the area here, we had a department store doing a gift-card "bonus" of 
10%.

What happened is, you buy a gift card (say, $300) they add an extra 10% 
to it ($30) giving you a total gift card balace of $330. You can then 
use the card to buy anything in the store.

The interesting part now comes in how to record where this 'extra' $30 
comes from, accounting wise? I'm half tempted to mark it as 'gift' 
income from the store, but am not sure that is right. If I were to do 
that, I'd put $300 on my payment vehicle, and $30 from my "income: gift" 
account.

IS this the 'right' thing to do? Sticker price for everything stays the 
same so all the receipts just show a payment with a gift card with $330 
on it.

Thanks

Jason