Big Business 14 updates the Qty Pricing Tab on the Item Card to improve useability.
Qty Pricing is separated from Item Pricing for clarity. As pictured, you see your price breaks for Qty's (10, 100, 200) sorted in ascending order. Click Add (+) for a new blank row and it goes on top (highlighted).
Qty Pricing is one of many optional tabs for items along with Item MRP, Price Levels, BigCommerce, and Shopify, pictured. Each is turned on separately so there are only three tabs to start. Go to Item Prefs, click Qty Pricing, and this will enable this feature.