You say that you want the grand totals of doctype, and yet your last post says you want the totals per job. If you want the subreport to show the grand totals across all jobs, remove the links between the subreport and the main report. If you want the subreport to show the totals per job, only link the subreport by job. In either case, you could still place the report in the doctype group header.
If you also only want to show the running total for the specific doctype, you need to use a shared variable. In the main report, create a formula:
whileprintingrecords;
shared stringvar doctype := {table.doctype}
Insert another Group Header #3 section, and place the shared variable formula in GH#3a, and then suppress GH#3a. Drag the original GH#3 fields and the subreport into GH#3_b.
Within the subreport, use field suppression so that only the doctype total corresponding to the doctype in the main report is displayed. To do this, you would highlight the running total->format->field->common->suppress->x+2 and enter:
whileprintingrecords;
shared stringvar doctype;
doctype <> "labor" //or whatever is the specific doctype the running total is evaluating
Repeat for each running total, changing the value in the suppression formula. You could lay the running totals on top of each other so that they would appear in the same position.
-LB