KA riss, with the first sound as in cat (listen to the top pronunciation here:
http://www.forvo.com/word/carys/#cy) If you want something pronounced care-iss, then
Cerys is closer.
It's a nice enough name and would go with almost anything, barring other ca- and -iss names and R & S names.
Carys Olivia Carys EmilyCarys JulietCarys ElinorCarys AnwenCarys JaneCarys Lily