Is there a way to set up smart volume discounts for subscribers versus having to set up individual pay items for different increments: i.e. 1 subscription is 19.99 until you get to 5 and then the cost per subscription is $89.99 or do you have to set up predetermined increments (i.e. product listing of 1-4 = 19.99 and allow people to specify quantity and then 5 = $100, etc.). Thanks,