The Collaborative International Dictionary of English v.0.48:
Tither \Tith"er\, n. 1. One who collects tithes. --Milton. [1913 Webster] 2. One who pays tithes. [R.] --Chaucer. [1913 Webster]WordNet (r) 3.0 (2006):
tither n 1: someone who pays tithes