No. Variable additional costs can be tied to the store's total revenue or to the number of orders, but they can't be filtered to a subset of orders.
For example, you can't apply a fee only to point-of-sale sales, or only to sales from one channel.
The alternative
When you actually pay that item, add it as a fixed cost with the real amount, and keep adding rates to the same cost month by month. That way it's accounted for with the exact amount instead of an estimate.