I am not the Running Total expert, DBlank is, but I do the same thing in code using formulas and shared variables.
depending on if/when you need to reset the values, the appropriate group header:
shared numbervar oneVar := 0;
"" //hides the formula
to display, in the appropriate footer:
shared numbervar oneVar;
oneVar
those are the easy ones, the hardest (which may not be) one is the increment in details:
shared numbervar oneVar;
if someCondition then
oneVar := oneVar + {table.field}; //or some value (usually a field)
"" //again hides the output otherwise you will see a running total
hope this leads to a solution.