Maybe.

Sale 1: Sold for 20 keys

http://backpack.tf/profiles/76561198141033153/#!/compare/1458716400/1459641600

Sale 2: Sold for Electric Hat Protector A Head Full of Hot Air[21 keys via mini]

http://backpack.tf/profiles/76561198071752472/#!/compare/1456732800/1456819200

Sale 3: Sold for 20 keys+Non-Craftable A Distinctive Lack of Hue[1 key]

http://backpack.tf/profiles/76561197972215762/#!/compare/1457424000/1457510400

20+1=21 keys

Sale 4: Sold for Magnetic Hat Protector A Head Full of Hot Air[22 keys]

http://backpack.tf/profiles/76561198047654421/#!/compare/1455955200/1456214400

Sale 5: Sold with 2 keys of sweets for Strange Specialized Killstreak Australium Flame Thrower[19 keys via mini](also had a part which adds 2.5 keys~ to the thrower]

http://backpack.tf/profiles/76561198047654421/#!/compare/1455868800/1455955200

19+2.5=21.5

21.5-2.5=19 keys

Mini for Hot Air:

Sellers at 21 keys https://gyazo.com/9ba66b663ea0660e1ea7394cd4098d9b.png

Mini on Flame Thrower:

Sellers at 19 keys https://gyazo.com/deabc97f3b2c9208828a1c2a75ab6585.png

So I have sales at 19, 20, 21, 21, and 22. Making this a range of 19-22 keys.

Oh, I messed my calculation up a little.

For sale 5, I messed up my numbers.

19+2.5=21.5

21.5-2=19.5 rounding to 20 keys

That means the correct range would be 20-22 keys. I think this is close enough. If it's not, feel free to let me know.