The allowed maximum number of decimals for the Invoice line charge base amount (BT-142) is 2.
//cac:InvoiceLine/cac:AllowanceCharge[cbc:ChargeIndicator = true()] | //cac:CreditNoteLine/cac:AllowanceCharge[cbc:ChargeIndicator = true()]
string-length(substring-after(cbc:BaseAmount,'.'))<=2