ms project courses - Calculating costs

Calculate summary rows for custom fields

On the Tools menu, point to Customize, and then click Fields.
On the Custom Fields tab, click Task or Resource, and then click the field type you want in the Type box.

In the Field list, click the name of the custom field whose summary row calculation you want to specify.
Under Calculation for task and group summary rows, click Rollup, and then specify the type of rollup value you want.