Level 2

totalTaxAmount

The taxAmount field on the InvoiceItem object

Total tax amount applied to the transaction.

Level 3

freightAmount

The shipping or freight cost associated with the transaction.

This field is set to 0 by default.

dutyAmount

The duty charges for the transaction, if applicable.

This field is set to 0 by default.

discountAmount

Discount for the transaction, if applicable.

It is calculated using the following formula:

SUM{ Discount * (ApplyAmount/InvoiceAmount) }