Your ability to do this depends on what the columns are. If they are unrelated fields, I don't think you can do this. If you have a manual crosstab, where each column represents a different instance of the same field, as in months based on the date field or service types based on a type field, then this is possible by using the advanced layout and adding the field as the "on change of" field, and the amount to be totaled as the summary field. Then, if it's a date field, you could select the "on change of" date field and click on "order" to recreate the group by month, e.g.
-LB