ER diagram for POS system

this is the our ER diagram for the SEP project and based on the ER diagram we planned to implement our whole system. it is very easy to implement the system after decide the basis of the system called ER diagram.
In software engineering, an entity–relationship model (ER model) is a data model for describing a database in an abstract way.

project new functions.... POS system --> Advanced POS system

As our project have some more functions and methods added here are the main categories (tables) which will be in our DB.

1.    Transactions

·       Cash

·       Credit/Debit Card

·       Cheques   à only for Suppliers

2.    Employee Details

·       Super admin

·       Sub admin

·       Accountant

·       Cashier

3.    Department à (optional)

·       Managing

·       Finance etc.

4.    Salary à basic, epf, etf, ot, bonus (for good employees àtrack)

5.    Supplier Details à contact no and address **

6.    Purchase order à many PO items and total for one supplier

·       Purchase order item

7.    Stock items à include expiry date and batch no **

8.    Invoice (Bill) à for customers

9.    Customer details

10.                        Credit customer details à cash exceed amount**

11.                        Tax à tax1, tax2, tax3, tax4 and value include % **

12.                        Bank Details

·       Bank accounts details

13.                        Utility Bills à water, electricity, telephone, internet etc.

14.                        Assets Bills à for long term items (chairs, tables, machines, PCs etc.)

·       Asset item

15.                        Vehicle details à transport services

16.                        Vehicle Finance Details (OPT)

17.                        Loans à employee loan (6,12,24,36 months etc.) deduct from emp salary

18.                        Cash handling à cash details about issuing to the cashier and balancing daily

19.                        Report Generating

20.                        Menu item à. For restaurants/ hotels