You can quickly calculate a fee by "Percent of Order" on a project by excluding logistics. For example, I charge a Rush Fee for jobs placed within one business day of the event. I can create this fee as a service and exclude logistics from applying to the project when I add it.
Follow the steps below to get started:
Navigate to the "Inventory" tab
Create the fee as a service or search for it if it already exists
Click on it and then click the pencil icon to edit it
Under "Basics", navigate to the "Pricing Structure" options
Select "Percent of Order"
Check "Exclude Logistics"
The final step is to add this Rush Fee to a project. You'll notice that this fee only applies to Rental Items and Services (i.e., the DJ and Bartender) on the project, excluding Logistics from the total.