Giveaway complete and a lesson learned

I recently ran a Good Reads giveaway to see if I could generate some additional interest around Dream Job. In the end I got 1150 entrants, a very respectable number for a self published first time author. However, even having discounted my book to $.99, I only generated 3 additional sales. Therefore, overall, I came out about $50 down. I am actually going to run another giveaway in about a month, just to see what happens if I only put up 1 book instead of 5. I'm guessing that it won't make any difference to the number of entrants.