Hi "reputationonly", my name is Shay, I am an accountant from Ireland, and I am new to freelancer, so I hope I understand whats going on properly.
I would suggest the specification you gave in the introduction is incomplete. I think you need,
1. Purchases (by month)
2. Sales (by Month)
and if you have a bank account
3. payments
4. receipts
5. bank reconcilation
of course if you have more than one bank account, you will want 3,4 & 5 repeated.
6. Extended Trial Balance
7. Income statement
8. Balance Sheet
The lay out will be dependent on the sort cost centers you have, but if you let me know what they are I can manipulated to suit.
Regards
Shay