This trip may also be the sort of trip where the Japan Air Pass may be a better choice, especially because you're going direct from Haneda to Sapporo.
Normally I'd not reccomend the air pass because it's such a hassle getting to and from airports that for most travel it doesn't make sense, but in this case, you may want to look into getting the air pass flights from Haneda to Sapporo, and then Sapporo to Nagoya Centrair.
Of course, I'm assuming you're going to fly out of Nagoya Centrair - if not, and you have to get back to Haneda for your flight back home, then the Rail Pass is the cheaper/better choice.