Difference Between Line Total and Invoice Total

Why do total amount of matched lines sometimes differ from the invoice total?

Sometimes on PO invoices, the matched lines (line total) differ from the invoice total. This discrepancy is usually caused by a price discount. To investigate, check the invoice in AX2012/D365 to see if a price discount is associated with the lines.

Example

Here you can see an invoice which's total amount of matched lines (line total) differs from the invoice total.

The line total is $118.75, but the invoice total is $100.00. 

1. Open AX2012/D365 and find the invoice.
2. Go to Lines > Price and Discount.
3.  Check if there is any price discount associated with the lines.
   The screenshot below indicates that there is, hence the line total and invoice amount mismatch.