Hmmm... interesting question. Personally, I would use .NET to build a new data source that does the calculations and print that. But to stay strictly in Crystal Reports would be tough. Not knowing you database structure makes it tougher. My initial attempt would be to create a bunch of formulas to do the calculation but even that doesn't seem like it will work. I wonder if you could create a subreport and use formulas with global variables to get your subtotals from that and then use formulas on these subtotals? Still a longshot.

Another idea would be do use SQL cursors within a stored procedure to pre-process the data and do the projections. Then return all the data as a virtual table.