Please Note: If you have different rates for delivery fees then they need to be created as non-inventory items and you must use a different name other than "Delivery Fee' specifically. You can name it "Fee for Delivery".
Question:
How do I create a taxable flat delivery fee?
Answer:
The flat delivery fee is set up in Configurations > Configs > eCommerce > General
Set your Delivery minimum
Choose subtotal or grand total to calculate the minimum
Set your Delivery Fee
Toggle the Taxable Delivery Fee to on
Navigate to Configurations > Configs > Taxes >
Configure the tax using the applies to "dropdown"