SKU management & shipping

hi, using the latest version of zen cart.

no problem yet. just trying to bat down the hatch on a few details.

one that has me scratching my head is SKU management. i'm going to be using the shipewire module for managing shipping and i'll have three options available.
(1) 1 of my bags @ retail price
(2) 5 of my bags @ wholesale price (using wholesale module)
(3) 10 of my bags @ wholesale price (using wholesale module)

(1 through 3) all have different sku's for shipwire so i'm wondering how i make sure that mr. wholesaler purchasing option (3) will get sent the box of 10 bags and not two boxes of 5...or 10 boxes of one bag (especially since that would kill me on shipping costs).

is there a place i need to input the SKUs? is this something i should add as an attribute (either hidden or publicly visible)?

thanks in advance!