To qualify for commercial account, and receive commercial discounts, you pretty much gotta be a commercial entity, and ship a pretty fair - and steady - volume.
Anticipate a fairly rigorous - but typical - business credit evaluation, calling for both bank and trade references, and figure on submitting a relatively detailed plan or prospectus of anticipated shipping and receiving acticvity over at least a one-year period. The amount of discount available will be determined by shipping volume, payment method and scheduling, and type of shipping desired.
Look
HERE for FedEx Supply Chain Services. UPS, DHL, Airborne Express, Roadway, and most other parcel services all have similar programs.