Hi,
PO price and taxes are different. I think the requirement is not logical as you mentioned. If you add the non-deductible taxes in the PO net price, the remaining taxes will calculate on PO price + Non Ded. Tax, which is not expected!. There is no use even if you add the non-deductible tax in PO net price - the GRN entry expected is same as in my previous comment! I would suggest to explain the same to client and convince!
If its a freight condition, there are different options as explained in the document: Tax Calculation on Freight - Different Scenarios
Regards,
AKPT