I'm pretty sure you can do this In the display text option of your totals, create a shared varable like so.
shared currencyvar TotalX := {your running total};
ToText({your running total},2);
In your main form, you create a forumal if you want it displayed
in your report by putting
shared currencyvar TotalX;
as its value.
If necessary, you may need to reset your varable before the next instance of your sub report runs.
To do this, again use the display text of a field in the main report which is run before your sub report.
shared currencyvar TotalX := 0;
ToText('what ever your field name is');