[ic] Common Adjust - how can I do this?

[interchange-users@icdevgroup.org (Russ Mann)]

Hello List,

I've read the docs on CommonAdjust, and I use it currently for quantity
discounts.  I want to try something new however, please let me know if this
is possible.

If a user puts item BSC into their cart, then all items in the pricing_group
COM will be quantity discounted.  If the item BSC is NOT in the cart, then
the items are NOT discounted.

The discounts would work like this:
1-4 - no discount, regular price
5 - set price = 20.00
6-9 - first 5 at 20.00 each, 6-9 at regular price.
10 - all at 20.00
etc.

Any ideas on how to make any or all of these features work?  Even if I could
only implement part of this, it would help.

Thanks,

Russell