This should be straightforward, but usually the table would be formatted where one column was "month" and another column was "sales", and it would look more like:
Jan 10
Jan 20
Jan 10000
Feb 20
etc. Then you would just have "month" as the Dimension and "=sum(sales)" as the Measure to get what you want.
What you want to do is use the FIELD NAME as the Dimension and sum the values of the field with the matching field name... Which may be possible but it is convoluted.
