I'd like to try a couple things, is it possible to upload the tbwx file?
I finally solved this. Not the way I wanted it to appear, but as good as I think I'll be able to get it.
I just created two data grids, one with the additional detail field, one with a constant of "total".
Then when I set my filters, I only applied the filter to the more detailed data grid instead of the with the totals.
On my dashboard, I'm displaying both data grids, but changes in the filter don't impact the "Totals" data grid.
Like I said, not as pretty as I'd hoped for, but it got the job done.