> If a refund takes place, you will also be refunded the following transaction fees:
> - The domestic processing fee (for example, the 2.9% fee)
> - The cross-border processing fee (for example, the 3.9% fee)
> Note that the Authorization fee and Disputed chargeback fee are non-refundable.
So it looks like Amazon Payments holds onto the 30 cents but refunds the variable part. It's obviously not zero, but for a $100 domestic charge Amazon's 30 cents is much less than the $29.30 that Stripe pockets.