If you want to rollup a field that contains product costs, you will have to change the field type. 1. Click on the small arrow in the product cost field tab. 2. Choose the “Rollup” field type. 3. In the “Rollup” tab, choose the field that contains the products (e.g. “Products”). 4. Then, select “Price” in the second drop-down menu. 5. Choose the function you want to apply to product costs. 6. Click “Save.”