Message

If TAX breakdown is present, the order agreement TAX total amount = Σ TAX category tax amount.

Context
/ubl:OrderResponse/cac:TaxTotal[cac:TaxSubtotal]
Test
(xs:decimal(child::cbc:TaxAmount)= round((sum(cac:TaxSubtotal/xs:decimal(cbc:TaxAmount)) * 10 * 10)) div 100) or not(cac:TaxSubtotal)