Hi,
Tax on material depends how material behaves to the business. If you want tax on delivery address- just create your favorable tax code and enter that tax code during your PO creation, and later on proceeding transactions(MIGO and MIRO) based on tax code nature, the tax will be calculated.
If want automatic tax code in PO creation, then enter tax code in creation of info record and see how tax code appears during PO creation!
Regards,
Biju K