Fee Rules Based On Order Value

Hi

We have a Rule Based fee that is set at order level to apply a transaction fee to orders, based on various modes of sale and price types. However, we only want that fee to apply to orders over a certain value. Our sales advisors can manually remove the fee if the order total is less than that amount, but the website cannot (we are using a custom website and TNMP for mobile).

Does anyone know of any way in Tessitura to only apply the fee if the order total is over a set value?

Thanks,
Chris.