Many of the companies that we work at have items that have varied DECPLQTY - The items might use 0 decimal places for the quantity, but some will use 1, or 2, or more.
This is a very difficult concept for .NET controls to grasp, so usually we just return all five decimal places.
This function will correctly format a decimal quantity to the required number of decimal places, and optionally add in the commas.
The return will be a string.
EDITED 12/23/2016 comma handling for negative numbers