There are certain objectives you need to complete (achievements), and for each one you complete, you get a gift (game or coupon) or some coal. Each coal you get, goes into the raffle as one entry :P
Any items you pick up from the ground (or throw on the ground) are still added one by one to your inventory, so you know how much stuff you have. However, you don't know how much stuff you're placing down. So it's okay if we're in creative mode :P