In the meantime, use Gyft to purchase at Amazon. If sales numbers are high enough, Amazon might take notice and decide to accept bitcoins directly, just to cut out the middlemen.
Or, if you want to just pay the item cost and not have to round up to the nearest $10, use snapCard.
Snapcard has a 2% surcharge. Gyft actually pays me 3% back on every purchase. There's nothing better out there.