Cumulative Sum based on preceding rows on a grid?

[#1]

Hello, so I have this grid that has two fields, one is a number of 'costs' per a 'department' lets say, and then another one for the cumulative costs as the department costs are listed under it (proceeding). Is there a script that can calculate the cumulative sum in such a way as to say in the first row take the cost, then in the second row, add both, then add all three in the third row? here's a pic for an idea!

Sum cum full will have .1647 on the first row, then the sum of (.1674+.2222) on the second row and so on!

Thank you!

Kurt

[swuehl]

Create an expression like

=Rangesum( Above( Sum(costs), 0, RowNo() ))