I haven't found a definite written answer, probably because it is implied. However, I'd really love confirmation if anyone can verify my assumption, before I make a decision.
Say I bought 10 shares of a stock at $10/share, for a total cost of $100. Now the stock is worth $20/share. Can I sell 5 shares, effectively pulling out the original $100 I put in and leave the other 5 shares to continue to grow in value without having to pay ANY capital gains tax at all?