Percentage Fees are for variable amounts you want to add to the order. For instance, you would use a Percentage Fee to add a 5% Damage Waiver Fee to your order.
Create a Percentage Fee just like you would any other Conceptual Item. But in the tick boxes in the bottom right of the browser window, be sure to tick the "Item is percentage" tick box.
You'll also need to tick the boxes to have the Percentage calculated based on Taxable Items, Nontaxable Items, or both.
For Percentage fees, once you've ticked the "Item is percentage" box, the "Rental Price" field will automatically become a percentage (rather than currency).
*The exception to this would be if your Percentage Fee does not apply to Taxable Items or does not apply to Nontaxable Items; whatever you've indicated the Percentage Fee does not apply to will not be included in the calculation.
When you add a Percentage Fee to an Order, it will only apply to the Line Items above it on the Order. Items that are below the Percentage Fee on your list WILL NOT be included in the calculation.
You can change the Percentage of your Fee using the "Unit Price" field. You can use this method to change any Percentage Fees on an Order-by-Order basis.
Also see our Percentage Fees & Discounts Tutorial