Could I gain 10% compounded every week by trading forex?

I am going to be 18 in 6 days. I have a practice account with FX Express. I’ve even bought Currency Trading For Dummies to learn what I need to know about trading currencies. With my practice account which is like the real thing, (apart from emotions!), I have been making 10%+ compounded every day. However, I want to be a little more realistic here and say with real money, I could maybe make 10% compounded a week with real money. I want to know is this is actually possible to do when you put in real money?

Day Trading and Taxes question? ?

Ok, I am very confused on how taxation works with trading stocks. Take the following scenario for example.

I buy for 60$ and sell at 80$. I make 20$ profit.
I buy for 40$ and sell at 30$. I lose 10$.
I buy for 50$ and sell at 100$. I make 50$ profit.
I buy for 70$ and sell for 4$0. I lose 30$.
I buy for 50$ and sell at 60$. I make 10$ profit.
I buy at 50$ and sell at 20$. I lose 30$.

Total profit before losses: 80$
Total losses: 70$

Profit left over at end of year: 10$

Ok, my question is… will I get taxed for the 80$ or will I be taxed for the 10$.

I have searched everywhere for this answer. It is going to kill me unless I find out!