Each row is it's own record. So if you have a formula it's only going to affect/pull data from that record. So there's two ways to slice this:
1) Create a summary report for this data
2) Create a fomula query, query all the relevant records for the data, and display a running total.
**3rd way, I don't know your app structure, but if these are child records to a parent, or could be, you could summarize that data at the parent level and do the calculation there.
------------------------------
Dwight Munson
------------------------------