Handling Fee is not something novel to many of us.
It is the amount that covers expenses related to fulfillment (warehouse storage cost, shipment cost, and packing cost).
Although this fee might not be applicable for every product in your store, it might be crucial for a more accurate Total Cost number.
With TrueProfit, you can now add and monitor Handling Fees easily.
See this Help Article for more detail.
Want to try this function? Install TrueProfit from Shopify App Store.