Less Than Minimum Fee - OSCommerce

I have an OSCommerce 2.3 website, and I would like to add a "Less Than Minimum" capability to my products, where if someone is to purchase under the applied less than minimum quantity, it will add a certain charge to their order. I want to be able to apply what the minimum quantity required is to each product, as well as apply what the charge will be to each product when the minimum isn't met. Not all products will require a minimum order though.