You can Make All these Items as Inventory and Put Quantity and Rate of Each Item
Purchase Name should be Like Purchase Local 5%,Purchase Local 0% Purchase Central 2%,etc
(it should not contain Item Name)
Step 1
While Making Company,Do Accounts with Inventory instead of Accounts Only
Step 2
While making purchase and sales ledgers,Do Yes on Inventory Values are affected
Step 3
Now while passing entry,it will ask for Item Name
Step 4
You can select Item Name or Create by Using ALT C
Put Item name
You need to Create Unit also (LIKE kg) by doing Alt C
Ctrl A to create unit
Ctrl A again to create item
Step 5
Now for item ,you can put quantity and rate
It will automatically calculate amount
Learn more
https://www.youtube.com/watch?v=aiKZpExoo4k