it would seem that a solution is yet to be found regarding this requirement.
Here's a bit of workaround to your problem:
this thread has made use of Indent Mode
I made a similar thing to calculate total for region and country.
You need to add in Amount dimension some different values for new different total and every single total need to join each value of Amount.
For example, you have Amount 200, 300, 400 and you want USD Total, EUR Total and so on...
You need to create a new dimension TotalAmount where you have a link for
USD Total to 200, 300, 400
EUR Total to 200, 300, 400
More all single Amount value, so
in your table you put the new dimension TotalAmount
I hope this help you.
Luca Jonathan Panetta