Word Origin & History
tanner
"sixpence," slang word first recorded 1811, of unknown origin. J.C. Hotten, lexicographer of Victorian slang, thinks it may be from tanner and skin, rhyming slang for "thin," presumably in reference to the smallness of the coin. (Not to be confused with tenner, slang for "ten pound note," which dates from 1861.)
[tan-er] 
ər