There are four common ways to price merchant services. 

Tiered: three to six rates (qualified, mid-qualified, or non-qualified).
One Rate / Enhanced Billback: one or two rates, plus surcharges for higher priced cards.
Interchange Pass-Through / Cost Plus: actual costs for each card accepted are “passed through” and clearly disclosed on the statement
Flat Rate: using a single flat rate for all cards. Most often seen as one rate for retail swiped merchants, and a higher rate for card-not-present merchants.

Please note that you can be overcharged with any of these pricing models, if you don’t do your homework.