Used on sales forms, a subtotal item totals the amounts of the items above
it, up to the last subtotal. You must create a subtotal item if you ever want
to apply a percentage discount or surcharge to several items.
Because QuickBooks calculates percentages only on the line
above, you must subtotal the items before entering a discount item that
calculates on a percentage basis.
To do this task
Go to the Lists menu and click Item
Click Item at the bottom of the list and click
Click the Type drop-down arrow and then click Subtotal.
Enter an item name, such as Subtotal.
Enter the description that you want QuickBooks to put on your sales forms
when you apply the subtotal.
Record the item.
How to change an item's type