It depends on how you are installing. There a couple of switches available.
For the Setup.exe method you can use two that I am aware.
|/rs||Reboot Suppress. Setup.exe will not initiate reboot even if it is required.|
|/rps||Reboot Prompt Suppress. If reboot is required, the system restarts without warning.|
For msiexec.exe then you have a Property that is available.
|REBOOT||Force or suppress rebooting.|