Message

VAT category tax amount (BT-117) = VAT category taxable amount (BT-116) x (VAT category rate (BT-119) / 100), rounded to two decimals.

Context
cac:TaxTotal/cac:TaxSubtotal
Test
(round(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent)) = 0 and (round(xs:decimal(cbc:TaxAmount)) = 0)) or (round(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent)) != 0 and ((abs(xs:decimal(cbc:TaxAmount)) - 1 < round(abs(xs:decimal(cbc:TaxableAmount)) * (cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent) div 100) * 10 * 10) div 100 ) and (abs(xs:decimal(cbc:TaxAmount)) + 1 > round(abs(xs:decimal(cbc:TaxableAmount)) * (cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent) div 100) * 10 * 10) div 100 ))) or (not(exists(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent))) and (round(xs:decimal(cbc:TaxAmount)) = 0))
Usage
/ ubl:Invoice / cac:TaxTotal / cac:TaxSubtotal / cbc:TaxAmount
/ ubl:CreditNote / cac:TaxTotal / cac:TaxSubtotal / cbc:TaxAmount