Question about Google AdWord pricing

I have been trying to figure out the pricing and rankings using the Google Tool at AdWord Tool
I use the word 'Soccer' and give it a max cost of $1.00. It comes back with a cost of $.46 and postion of 1-3.
If I increase my max. cost to $20.00 the cost goes up to $1.02 but the position stays the same.

Is the point to find the lowest possible max cost and still reach an acceptable position? If that is the case why is the price changing when I change my maximim cost?

Thanks