I'm a bit disappointed that my initial interpretation of 0% tolerance meant that it would work with colors exactly the color that I wanted, but apparently now I think 0% tolerance means working with colors with < 1% variation.
To demonstrate two close colors:
make a square colored: Red 119, Green 82, Blue 33
make another square colored: Red 120, Green 82, Blue 33
and then use a tool with tolerance on it set to 0%, and it treats the two as an identical color.
How can I work with exact colors?