There's actually no toll to cross the Queensboro Bridge.
The Queensboro Bridge is operated by NYC DOT and any bridges or roads operated by NYC DOT require no tolls to cross them.
So you can cross the Queensboro Bridge with no toll.
NYC DOT owns, operates, and maintains 789 bridges and tunnels throughout New York, including the Brooklyn, Ed Koch Queensboro, Manhattan and Williamsburg Bridges, 24 movable bridges, and four tunnels.
There are no tolls on bridges operated by NYC DOT.
So you can cross the Queensboro Bridge or any of those NYC DOT owned and operated bridges as many times as you want too or need too without paying a toll to cross them.