On Account sale Xero Error: The line total does not match the expected line total.

Problem

Posting an On Account sale to Xero results in this error: 'Bad request. A validation exception occurred - The line total does not match the expected line total'

Setup

• Retail POS for Mac or PC
• Xero integration 

Cause

A rounding discrepancy between Xero and Retail POS due to the way the tax amount on that On Account sale is rounded down to 2 decimal places. 

Can be caused by:

• Tax rates with multiple decimal places
• Line item discounts with multiple decimal places
• A large number of products in the sale

Solution

The On Account sale must be accounted for manually in Xero.