I've been meaning to get back to this.

Sign the Peace Tree-ty

http://backpack.tf/item/241854238

Sale 1) Sold for a Terror-Watt Caribbean Conqueror (21 Keys)

http://backpack.tf/profiles/76561198260486392#!/compare/1478044800/1478649600

Conqueror Mini

http://backpack.tf/profiles/76561198021324906#!/compare/1474156800/1474243200 - Sold for 21 Keys

Sale 2) Sold for a Steaming Airdog (13) + Stormy Storm Bombing Run (12 Keys) + Strange Teddy Robobelt (1.2 Keys)

http://backpack.tf/profiles/76561198094581085#!/compare/1478908800/1478995200

13 + 12 + 1.2 = 26.2, which rounds to 26 Keys

Airdog Mini

http://backpack.tf/profiles/76561198053928031#!/compare/1479772800/1479945600 - Sold for 13 Keys

Sale 4) Sold + 7 Keys for a Steaming Brown Bomber (28.5 Keys)

http://backpack.tf/profiles/76561198287685317#!/compare/1480291200/1480377600

28.5 - 7 = 21.5 Keys, which rounds to 22 Keys

Sale 4) Sold for 25 Keys

http://backpack.tf/profiles/76561198043936328#!/compare/1480377600/1480464000