Database design for multi-user POS system

I am trying to develop a POS application that has three points: -

• POS application terminal (in the same store, several) - for selling a product (Mutiple-terminal in the same store) Each terminal must have a local database for its own inventory list and invoice. (Local database to avoid internet crashes).

• Backoffice (in the same store, one, local database). Act as a parent for all POS application terminals to get report and price update for the entire POS application terminal. The entire POS application terminal (on one site) will send data to this database to generate a report such as the total volume of items sold.

• Headoffice (the remote database will receive data from the entire backoffice database). This database will get data from all back offices from all sites from different locations. can send price update to all backoffice systems and whole POS application terminal.

Can someone please tell me which type I should be using or some database replication tool can help me in this state.

Currently my application is completely out of the box and works with a single local database if I need to redesign the database or whatever to make it usable as I mentioned above. I am ready for any major changes.

I am using Hibernate

both ORM and MYSQL

as a database.

thank