It's tricky.
If you have a $100.00 Amex, Visa, etc. gift card and you want to load it to Amazon, there are a lot of steps.  First, you have to add the $100.00 card as a payment method.  Then you have to "add" money to your Amazon gift card and only add $99.90 (because Amazon causes $0.10 to be charged to that card as a verification).  Then you have to go back and add the $0.10 later.  I'm not sure why Amazon made this so difficult.
Rating: 4 stars