Develope simple platform for daily sales records

This will be a very simple platform to be used by a small local bar. The system will be used to keep a daily record of transactions and should include the following; Opening balance Cash Added Closing Balance Sales Cash Out Total Cash In Till Most values will be entered by the user, the system needs to make basic addition and subtraction to derive the totals. The amounts will be added once daily but the system need to provide a record of past transactions. It needs to be web based to offer ease of access. In the near future it might be also used for stock taking etc so upgradability and modularity have to be part of the design. A solid and intuitive design is also a must. Thanks and Best Regards, Gordon