OpenCart 1.5 conveniently provides the ability to backup or restore database files within its interface.  The following tutorial will guide you in using these options.

How to Backup or Restore your OpenCart 1.5 database files

1. Login to the Administration Dashboard as an Administrator
2. Hover over the menu bar where it says SYSTEM and then click on BACKUP/RESTORE at the bottom of the drop-down menu
   
   
   
   
3. Select the database tables that you wish to backup, then click on BACKUP
4. After selecting BACKUP, you will see the prompt asking you to save the file.  Make sure that you save it somewhere that you can find it again.  Once you have saved the file, you can rename to something more meaningful, such as:  backup10-11-2012. 
   
   OR
   
   Select RESTORE, then select the Browse button to identify the file that you trying to restore.
5. If you intend to keep multiple copies, please rename the backup file (backup.sql) to another name that will allow you to identify the file. 

The Backup and Restore feature built into the OpenCart 1.5 is a great feature, but I recommend making use of full site-backups if it all possible.