Have you looked at the rounding options from the Item Price List Maintenance - Options button? You can define a rounding policy (None, Up, Down or To Nearest), then a rounding option (Multiples of, or Ends in) and an amount. So you can instruct your pricing schedule to round up to a price that ends in '5' for instance.
I don't believe that the options are included in the Price List Wizards though which would mean they'd have to be setup on an item by item basis.