Secondary tax amount (only applicable in some countries).
This property is used to record the second tax amount in countries where more than one type of tax can be applied to purchases. This amount must be included in the TransactionAmount of the original transaction.
This amount is to be presented with an implied decimal point. For example, US $10.00 must be represented as 1000, and $0.10 is likewise simply 10. The allowable number of significant digits as well as the positioning of any implied decimal point is dictated by the designated CurrencyCode configuration setting. In the United States (default), the number of allowable significant digits is seven. Thus the maximum TransactionAmount is "9999999", yielding a US dollar amount of $99,999.99. This field may not contain a negative number. This property is only used for MasterCard Corporate Purchasing Cards (CardType = ctMasterCard).