I am not able to get Arbitrary Quantities to work on my pricing files

PRESSERO > *Pressero FAQs
The testing tab is there to let you test out various settings for the calculator. None of the settings you make there, including arbitrary quantities, number of decimal places, or min or max quantities, will be saved anywhere. They are reset each time you return to the testing tab, and do not apply to any products.

You must edit the individual product that uses the pricing engine, and set the arbitrary quantities there.