You can set different price tiers for customers under the Inventory Settings tab from the Setup Wizard.

(Price tiers on a product level is done in Edit Product – see the Inventory help section for more information).

Go to the Setup Wizard (gear in lower left corner).  Then click on the green Select button under Settings.

To add a new price level, click on the plus sign (+) next to “New tier code”.

Enter a code, name and the percentage of discount for the price tier. The discount will be calculated from the normal selling price of the item. Click Save price tier when you are done.