The SoundingRounding.xml file controls what sounding rules are applied to sounding display.
The file is located in the ...\System folder. HPD reads sounding rounding options in the file and these options can be accessed through the Properties window.
You can modify an existing file or create a custom file. You should retain the original SoundingRounding.xml as a backup.
The sounding rounding file is referenced by environment variable uslXSndRndCfg. If you create a new file, you will have to modify the variable in the Registry Editor.