Excel – Adding a cumulative sum column to a pivot table

I have a pivot table where I am representing a series of data across a number of categories as follows:

Sum of amount                     Area
Status     Priority    Project    Department 1    Department 2    Grand Total
In-flight  1a          P1               10,000                         10,000
           1b          P2               30,000                         30,000
           2           P3                               28,000         28,000
           3           P4               15,000                         15,000
In-flight total                         55,000          28,000         83,000
Pending    4           P5               16,000                         16,000
           5           P6                                1,000          1,000
           6           P7               30,000                         30,000
Pending total                           46,000           1,000         47,000
Grand Total                            101,000          29,000        130,000

I would like to add a column on the end of the pivot table that shows a cumulative running total of the Grand Total column amounts. Ideally I would like to preserve the pivot table properties, i.e. I would like to add this cumulative sum column and still be able to add and remove fields from the table. Is this possible?