Not a critique, but possible embellishments ... (respectfully)
heads for pennies, tails for dimes,
orientation of coins changing from upside right to upside down ... in opposing directions coppper vs. silver
I suppose you could also contrast the government heavy (dime) FDR "New Deal" platform with the more liberal "Emancipation" and freedom policies from (penny) Lincoln's presidency. But that might be going a bit too far
I appreciate all of the comments, it is always nice to hear what others think.
To be honest, I really hadn't thought of all the possible interpretations of change when I planned the shot. Its fun hearing what you all come up with!