cmd _cart Payment info in Return URL

cmd _cart Payment info in Return URL

Is there a way to get the payment info in the Return URL?
Just the final amount paid is all I need.
I am using:

name="cmd" value="_cart"
<input type="hidden" name="return" value="mypage">
I tried: < input type="hidden" name="rm" value="2">
But can't see any variables.
Thanks in advance!