Most efficient would be to start rounding purchases to the nearest five cents (if is isn't electronic) and get rid of the penny which costs more to produce than the penny is worth.
If the cost of metals in a coin is more than its value, you do have a point.
Every time I return from Germany I have a handful of 1 and 2ct coins though, since they haven't done this, and most prices are X.99.
With respect to the 1c and 2c coins, isn't the metal in them worth more than the currency value?