I have to create a purchase order approval system that has following workflow requirements

Depending on which division, Capital or non capital purchase, IT or not IT related purchase, cost under 5000, 5000 to 10000, and 10,000 and beyond, different approvers are assigned.

I created a list with following columns:

Division, capital yes/no, IT yes/no, under5000approver, 5000to10000approver, 10000upapprover

So when a PO is created I want to create a workflow to find the correct approver, but when I use the function button to "Lookup for string" I can only set one filter on either division, capital, or IT to give me the approver.

How can I use all the criterias to find the correct approver? Is there a better way to do this using SPD?

Basically I need to do a lookup on a field from a list using a query format like for example for PO under 5000

select under5000approver where division = X and capital = 1 and IT = 0