If you don't need the column values, you don't really need a crosstab. You would use the column field (from your crosstab) in your detail section, insert a summary on it, and suppress the details.
If you were creating a manual crosstab, and using formulas like:
if {table.value} = x then {table.amt}
...where "x" is a value specific to a particular column, again you would just add {table.amt} to the details instead of adding any conditions in a formula.
If there is some reason you need the crosstab format (e.g., for consistency) and still want to display only the total column, remove the column field to get a display with only the row totals.
-LB