When you setup your pricing to calculate installation, shipping or measure charge to be calculated as a percent of the item price, and to also include the installation, shipping or measure in the item price, the item price is not calculated correctly.
This is caused due to the way the software calculates the price. It cannot calculate it correctly because the item price is based on the installation, shipping or measure charge, but the installation, shipping or measure charge is based on the item price.
The only known workarounds are to either set installation, shipping or measure charge to calculate as a percent of retail price or some other method other than percent of item price OR to not include them in the item price.
Solatech has confirmed this to be a problem with the software listed at the end of this article. As more information becomes available this article will be updated.