Yes, DECILES is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, C 3, I 1, L 1, E 1, S 1.

Is it a valid word?

DECILES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(statistics) any of nine points that divided a distribution of ranked scores into equal intervals where each interval contains one-tenth of the scores