The SoundingRounding.xml file controls what rounding rules are applied by CARIS when displaying a chart.
The file is located in the following directory by default:
C:\Program Files\CARIS\<CARISApplication>\<version>\system
CARIS reads the sounding rounding options in the file and these options can be accessed through Tools > Options or the Properties window.
You can modify an existing file or create a custom file. However, you should retain the original SoundingRounding.xml as a backup.