Quote from: mmortal03 on July 02, 2011, 03:47:18 AM

Please explain. I thought is was a flat 0.65%? How do you get 3 x 0.65?

You don't. The fee is applied once to each side.

Example:
Alice buys 100 BTC from Bob for 10,000 USD.
MtGox applies the standard fee (0.65%) to both parties.
Alice gets 99.35 BTC. Bob gets 9935 USD.

So if you make a single trade, you pay the fee once, as advertised.
If you make a double trade (such as buy and sell higher, or sell and buy lower) you have to pay the fee twice (of course), so to break even you have to gain 1.3%.