Another variation on that suggestion would be to have an extra price column in the cart for the discounted members. You can then just bind this value to the other column and use the calculations to use one price over the other. This way would also show on a per item basis rather than all at the bottom but the benefit would be that the user can login after adding items to the cart to still get the discount rather than adjusting the price that is added to the cart if a member is logged in.