I have someone who wants a commerce website. They currently have an ebay store (zerksplus.com).
This is the store description "ZerksPlus is a supplier of Industrial Hardened Steel Grease Zerks, Nipples, Fittings, Couplers, Button Head and Adapters for Hydraulic and Flush zerks. Many zerks are available in Stainless, Monel, and Brass. Fittings come in many thread types including SAE, British, Metric, and Special Threads.".
They want a site (not on Ebay) that offers volume discounts. I have never used Magento and thought this may good be a good opportunity. Does have a feature offering volume discounts?
Yes Magento have lots off features and good for ecommerce websites, you can find more reviews from Google
Answer of you question, through magento you can set promotional rules Ans also customize discount rules as per you need by developing custom extension.
Hope it helps you