And nobody answered on my question : Is 10 USD fee NORMAL?
First of all, I've checked your numbers and in my case they are different. 669.96670022 and 666.62522041. On the right side I have 666.62522041 instead of 668.something, even worse than you.
Also if you enter the same number in a different order, the results are different (LOL).
Now the answer to your question, with my numbers:
0.39242276 * 1703.00000009 = 668.29596031
left side: 669.96670022 - 668.29596031 = 1.67
right side: 668.29596031 - 666.62522041 = 1.67
1.67 / 668.29596031 = 0.0024 = 0.24%
I knew of 0.20% fee, but it looks like it's closer to 0.25%.
However, the math looks pretty good imho.
Edit: I don't get your 10$ math. I've set the same numbers in the first cells at left and right to make everything correct and not compare apples with oranges. I hope that you have understood mine.
10 USD for crypto to go up to get any plus of 1 USD..Look one more time at the numbers.You see 1703 bought price and 1707 selling price..That should be 4 USD earning right? When you take SELLING fee 0.25% that would be $4 - $1.6 = 2.4 USD
Im in MINUS 1 USD so that means they actualy stole me 3.4 USD on this trading.
However, this NEVER happened to other sites, my friends doesn't have this crazy fee at other sites, we tested Poloniex and it's working perfectly just like the numbers were shown.