Green’s Dictionary of Slang

(US) a dollar; thus money.

1881		‘Bill Nye’ Bill Nye and Boomerang 22: This statement I am willing to back up with the necessary kopecks.
1912		Day Book (Chicago) 15 Aug. 24/2: It takes something bordering on an earthquake ro make him loosen up a few kopeks.
1914		Ade ‘The New Fable of Susan and the Daughter’ in Ade’s Fables 221: By stealthy short-weighting of the Country Trade and holding out on the Assessor, he succeeded in salting away numerous Kopecks.
1917		Van Loan ‘Levelling with Elisha’ in Old Man Curry 29: Elisha can win any time they get ready to cut him loose with the kopecs.
1919		Lima (OH) News 5 June 6/3: Coins are called [...] ‘kopex’.
1921		C.S. Montanye ‘The Bounding Violet’ in Top Notch 15 Aug. 🌐 I — ah — sold the contract to him for a thousand kopecks!
c.1935		‘Mae West in “The Hip Flipper”’ [comic strip] in B. Adelman Tijuana Bibles (1997) 100: Lotta planked that ten thousand kopeks down.
1943		R.L. Bellem ‘Feature Snatch!’ Dan Turner - Hollywood Detective Feb. 🌐 The latest Supertone costume opus, a stinker costing copious kopecks.
1974		G. Radano Stories Cops Only Tell Each Other 57: But if one [gambler] did make a squawk Fred could say, ‘Did you ever in your life pay me as much as a kopeck? Have you ever even seen me before?’.