Nobody asking for 5.5 keys is getting any luck since there are lots selling for 4-5 keys

http://www.tf2outpost.com/trade/8977484 - 5 keys

http://www.tf2outpost.com/trade/8646006 - 4 keys + wrap offer

http://www.tf2outpost.com/trade/8922593 - selling for 4 keys + wrap

http://www.tf2outpost.com/trade/8871151 - sold wrapped for 6 keys (hat for 5 keys wrap for 1 key)

http://www.tf2outpost.com/trade/8989298 - selling for 4 key + wrap

http://www.tf2outpost.com/trade/8963871 - selling for 2 keys + wrap

http://www.tf2outpost.com/trade/8955507 - 6 keys his wrap (wrap for 1 key and hat for 5 keys)

http://www.tf2outpost.com/trade/8925472 - selling for 4 keys + wrap

http://www.tf2outpost.com/trade/8936423 - selling for 4 keys + wrap

http://www.tf2outpost.com/trade/8908355 - selling for 4 keys + wrap

So it doesn't really matter if you count wrap as a key or you don't count it at all, either way there are still none selling for 5.5 keys