credits to '[F2P] Mr.Giang' & '-[FF-A]- Mindacos' for feedback!

Sale 1:

Sold for 17 keys pure ([17/19]) = 0.89 (rounding to 0.9)

http://www.tf2outpost.com/trade/21629693

Sale 2:

Sold for 16 keys pure ([16/19]) = 0.84 (rounding to 0.8)

http://www.tf2outpost.com/trade/21555375

Sale 3: (invalid sale)

Cannot identify sale through backpack history

http://www.tf2outpost.com/trade/21887210

Sale 4:

Sold for Dead Presidents Snaggletooth (1.15*0.9) = 1.035 (rounding to 1)

http://www.tf2outpost.com/trade/21052638

http://backpack.tf/profiles/76561198055555588?time=1406050472 → http://backpack.tf/profiles/76561198100532201?time=1406012400

Sale 5: (invalid sale)

Sold for a CS:GO Knife

http://www.tf2outpost.com/trade/21315344

Sale 6:

Sold for 16 keys pure ([16/19]) = 0.84 (rounding to 0.8)

http://www.tf2outpost.com/trade/21887875

Notes:

http://www.tf2outpost.com/trade/21889719 - B/O of 1 bud

http://www.tf2outpost.com/trade/22225733 - B/O of 20 keys (~1.1)

http://www.tf2outpost.com/trade/20658484 - B/O of 1 bud

Feel free to support/counter my suggestion!