Quantity Breaks is now available to install from within Custom Pricing. Previously, these two apps were incompatible out-of-the-box and required a custom installation. They're now built together as a solution that allows you to offer quantity-based discounts to your wholesale customers.
You do not need to install or enable the wholesale aspect of Custom Pricing to use Quantity Breaks.
If you already have Custom Pricing installed, visit Change Your Price Plan in Custom Pricing for more information on how to enable or disable the app's modules.