Dedicated "Shipping & Handling" Sub-Total By Location/System

We're not satisfied with using misc. items for shipping and handling because our clients are typically looking for shipping to be included in our system/location sub-totals. Our workaround has prevented us from having an additional sub-total from generating on the Project Summary.

We'd like a solution that allows a new sub-total to populate on the Project Summary while allowing us to assign shipping costs by system/location.