Here is a workbook that shows how it can be done.
The calculated field is TOTAL(SUM(Sales)). When included in the level of detail, it can be used in titles, captions, and tool-tips.
Grand Total in Title.twbx.zip 82.6 KB
I'm trying to replicate this, but I'm getting a range in the title instead of just the total number. I am using total(sum(value))... not sure how to work around this!
I was able to get this to work...I had the same issue as Amy, but when I changed the table calculation to "Compute using table(across) or table(down)" this solved the problem.