How do I show a particular row if a value (total) changes?

[jmoore]

I have a generic report which basically has data as follows:

CSA Month Cost
1 M1 50
1 M2 50
1 M3 100
1 M4 50

2 M1 25
2 M2 25
2 M3 25

3 M1 75
3 M2 50
3 M3 75

I want to have another report that only displays when the Cost changes, i.e.
CSA Month Cost
1 M3 100
3 M2 50

Any ideas on how to achieve this? The model is DMR and the reports are currently List.

Thanks.