You may want to exploit some properties of your data, namely,
the existence of [Category] = 'Total' dimension value.
With that you'd skip the [Category] dimension Sub-Totals --
leaving only Row Grand Totals on the view.
You may want to use Measure Names / Measure Values
(as the rightmost pill on Columns) to get the desired layout.
Please find the attached.
Totals Column Addition_v10.3_YF.twbx 138.0 KB
Unfortunately it is a little more complex than that and it lost the levels when I posted. We are unable to post any workbooks as it is all proprietary but we were able to find a way around the issue. I'm not sure how the developer did it, as I am not actually on this project was just looking to help them out and learn something in the process.