Running total option:
Create a Running Total called "Billable and non-billable" (or whatever you want) by a right click on running total and select new.
Field to Summarize: column 5
type of summary: sum
evaluate: use a formula (mark that and clcik on the X-2 button) foumla is
{table.column4} <>"Total"
Reset: on change of group1 (assuming that is where your column 3 name is grouped).
Place the field in group FOOTER 1 (running totals only work in footers not headers)
or use a Formula option:
create a formula by right click on formula field and name it "Hours to Sum" (or whatever you want).
in the formula put:
{table.column4} ="Total" then 0 else {table.column5}
You can place this formula on your detail record to see if it is correctly inserting zeros or the hours where you want it to.
Create a Summary function by click on the Insert SUmmary button
Field to Summarize: x-1 Hours to Sum (will show up as {@Hours to Sum} in a formual)
Calculate this Summary as a SUM
Summary location at group 1.
This can be placed in group footer1 or group header1.