The SoundingRounding.xml file controls what rounding rules are applied by CARIS when displaying a chart.
The file is located in C:\Program Files\CARIS\<application>\. CARIS reads the sounding rounding options in the file and these options can be accessed through the Properties window.
<version>\system

You can modify an existing file or create a custom file. However, you should retain the original SoundingRounding.xml as a backup.