I'm not sure the 512 shares out of ~100,000,000 shares in my example is worth anything. My example is worse than that as it is 512 shares in 3 shifts (~300,000,000 shares).
Unless the price of Bitcoin (currently ~$450) goes back up, CPU mining is just a little above break even (unless you get free power). I just turned my Primecoin miner off as I think it is a loss for me after A/C costs.
Edit: 1 Share at 512 diff is 512 shares (I think)