Green’s Dictionary of Slang

ten per cent house n.

(US) a cheap, poss. crooked, casino.

[US](con. mid-19C) H. Asbury Sucker’s Progress 185: Those extraordinary gambling dens genrally known as Wolf-Traps, but sometimes as Snap Houses, Deadfalls and Ten Per Cent Houses, are said to have originated in Cincinnati about 1835.