To “throw nickels like manhole covers” is not to throw nickels at all. (Manhole covers are heavy and are almsot impossible to throw.) The saying implies that a person is stingy with money.
 
“Pennies ‘like manhole covers’” was cited in print in 1963. The saying became popular in sports, when players were negotiating for contract increases against penny-pinching managements. “Calvin throws nickels around like manhole covers” was said by a baseball player about the team owner in 1965. “George Halas tosses nickels around like manhole covers” was said by a football player about the team owner in 1967.
 
 
15 December 1963, Lubbock (TX)

, pg. 2-H, cols. 2-3:
PENNIES “LIKE MANHOLE COVERS”
Price Of Phone Calls In Britain Is
Lowered; Savings On Clothing Slated
By JIM BECKER
LONDON (AP)—The nickel phone call may be extinct in the United States, but in Lodon the four-cent phone call has gone down to three.
(...)
English pennies are approximately the size, the weight of manhole covers.
 
Google News Archive
13 September 1965, St. Petersburg (FL) Times, Jimmy Mann sports column, 6-C, col. 1:
Jim Kaat, the fine lefty who has won five of his last six starts for the Twins, was a holdout this spring and claimed, “Calvin throws nickels around like manhole covers.”
(Calvin Griffith, owner of the Miinesota Twins.—ed.)
 
Google News Archive
15 March 1967, The Free Lance-Star (Fredericksburg, VA), “Batting the Breeze With Buttram” by Bill Buttram, pg. 26, col. 1:
Mike Ditka, Chicago Bears tight end: “George Halas tosses nickels around like manhole covers.”
 
Google Books
The Multimillionaire Straphanger:
A Life of John Emory Andrus
By George P. Morrill
Middletown, CT: Wesleyan University Press
1971
Pg. 117:
The Burns clique snorted…oh sure, Mr. Andrus was reported to throw quarter tips around like manhole covers.
   
Google Books
Newsweek
Volume 78, Issues 18-26
1971
Pg. 55:
But Halas’s parsimony was best summed up by end Mike Ditka: “He throws nickels around like manhole covers.”
 
Twitter
Mihir Bhanot
‏@mihirbhanot
“You’re throwing nickels around like manhole covers” - @pointsnfigures on ppl who nickel & dime early valuations - ep8 @TheFullRatchet #QOTD
California, USA
10:43 AM - 13 Aug 2014