volume discount, wholesale / reatail

I have a need to set up retail & wholesale groups with different volume discounts.

inventory example would be as follows:

retail
quantity 1-2 = $5
quantity 3-5 = $4
quantity 6+ = $3

wholesale
quantity 50 - 100 = $2
quantity 100+ = $1

so, I have 2 groups that need multiple pricing for different quantities. These retail and wholesale quantities need to be applied to an inventory of 5000 items.

Besides just asking the obvious "How do I do this?" My questions are:

How do I create these quantities across all inventory categories/sub categories, and how do I get attributes to sort them by group?

I've worked with Zen Cart long enough that I know this can be done, but not long enough to just go ahead and do it. Any help would be appreciated.