Hopefully someone can help here.  We currently sell about 500 items.  The items can be broken down into two groups. The groups are Insulation and Accessories.  We have 5 different price levels with insulation, which we assign to different customers depending on their credit and purchase history.  For accessories, we sell them at 20% markup no matter who the customer is.

My question is how do I differentiate these two groups?  I understand how to set up price levels and assign a price level to a customer for insulation products, but how to I assign a 20% markup on all accessories, no matter what the price level for insulation?