Is it possible to use the Order Total (after modifiers applied to lines) as the qualifier for a free

It appears that when setting the 'Line Qualifier' Context = Volume; Qualifier Attribute = Order Amount to a value range, that the Range is evaluated against the List price * the Qty before discounting.  Is it possible to have the Order total as the basis for qualifying. We want to give free freight offer for orders over an order value of $500 however discounts will allow orders well below that amount to get free freight as well.