I know that money acquired through the sale of stock is taxed, but is the difference between the initial and final amount taxed, or the entire amount?

I remember seeing a tax bracket table where the smallest percentage was 10. How can anyone make any money below 10% growth if that is exactly the amount you are taxed?

You only get taxed on the gains or losses. If you invest 100 and sell for 150 only the 50 will get taxed. Also, if you invest 100 and sell for 50 you can claim the 50 loss as capital loss.

This are called Capital Gain Tax or Capital Loss.