Like many of the features in Roon, you get to decide! Go to Settings>General>scroll to Browser Sort preferences>Name for compilation sorting, to set your sorting preference.
Select Use "Various Artists" if you want all of your Various Artists soundtracks and compilations sorted together under "V" in the album browser. Or, choose Use album title if you'd like your Various Artists compilations and soundtracks sorted alphabetically by album title in the album browser.