Hi,
Two suggestions (untested!!)
If all you need is a count of TRUE or FALSE values, you can simple group by your Boolean Formula, and then add a summary field (count type) based on a field in the details
If your report is already grouped in some other way, then you could create a running total (count type) which will be reset to zero on change of group and updated using the formula... {@bool_expr}
Similarly, for FALSE, update formula... not {@bool_expr})
Hth,
Geoff