Charging delivery fees

Hi,

It's a common practice to charge delivery fees in case of pharmacy wholesale distribution.It depends on the number of orders placed during the day before the cut off time period. It needs to be invoiced to customer either through invoicing process or through debit notes.

I wanted to understand what is the best practice for handling delivery fees in SAP. It cannot be in the sales order. Should it be put in the invoice directly or raising debit memo is the best option