Hndling item-wise charges in PO

In a purchase order, we want to include the other charges such as boxes for packing the items, labor charges, unloading charges etc.

Some charges can be treated as ‘Actual’ in tax and charges template while other charges are based on a per unit rate (e.g. rs 30 per box) and the amount varies depending on the number of boxes required in each case. Such charges are to be computed and shown on a per-item basis.

What is the best way to handle this in ERPNext?