Add calculated fields to HubSpot Pro level

I believe I need somthing similar. Curently we are using PandaDocs because the HubSpot quotes are just not there yet. We too are a manufacturer with list price and discounts for wholesale. Idealy we want to quote list price(A) then a percentage discount(B) followed by a discount applied price(C= A*B). After that we add in quanity and have a line item subtotal. Our goal is to reduce sticker shock and show the value of choosing to carry our products wholesale.

Our products have different percentage discounts so doing a flat discount after the subtotal will not work.