Randall Munroe does the math to prove it:
How much is your time worth? This obviously depends on a lot of things and varies from time to time and person to person. But for a broad estimate, I sometimes use a ballpark value of $10/hour—which is somewhere between the US minimum wage and the average wage—but you can adjust up or down to fit your preference.
If your time is worth $10 an hour, a penny is worth 3.6 seconds. If spotting and picking up a penny takes you more than 3.6 seconds, it’s a loss.
He goes on to calculate the cost and value of a penny given numerous other considerations.