It doesn’t have to be same currency, you can add taxes in currency 1 to suppliers purchase invoice in currency 2 by converting the taxes using an exchange rate and adding as Freight-in to the purchase invoice.
Read through this lengthy but worked solution topic Importing of goods
But this wont add / spread those costs over the actual inventory items involved as requested:
“Customs paid should be reflected in Inventory items since customs duty is adding cost to the Inventory items”
Besides, as you will never sell “tax” or “clearance”, those inventory items will never decrease in value unless you journalise them to P&L expenses.