Get Gift Card amount in Shop Money

[osakachado]

Hello! Using API I am getting the order and transaction information for orders. When an order is paid in a foreign currency using a gift card in USD, how can I find how much of the Gift Card was actually debited? 
For example, a recent order was placed in Japanese Yen. They used a USD $50 gift card and paid the rest using JPY Paypal. On transactions.json it only tells me that 5800 JPY of the gift card was used, but there is no indication of the exchange rate or Shop Money value there. How can I find (using API) that this is $50?? We are tracking our gift card liability, so we need to know how much gift card was actually used. Of course I can manually see this info on the order screen. I want to figure out how to get it programmatically. 

Thank you!

[osakachado · Accepted solution]

Ok, so I answered my own question. I found the Gift Card amount in the Store Currency using the payment section of the Checkout API. It was listed as amount_used:
Here is Shopify's help on this section:

Retrieves a list of payments on a particular checkout

Payment (shopify.dev)