Yes, TENNERS is a Scrabble word!

Letter values in Scrabble US: T 1, E 1, N 1, N 1, E 1, R 1, S 1.

Is it a valid word?

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

the cardinal number that is the sum of nine and one; the base of the decimal system
a United States bill worth 10 dollars

Also: 10, x, ten dollar bill.