Feature request from kassner, posted on GitHub Nov 16, 2015
Hi,
On the new Credit Memo form, the field Grand total is not updated when you change any value in the Refund totals block.

In the image above, please note that the Grand total is $20.00, even though the Subtotal is $10.00 and the fields below are $0.00. When you change any of those fields, the Grand total is not updated.
Thanks!