Depends on which country you sign up as....if US, then it is $1 for US$1.
If you sign up as UK , then it is $0.57 for Pound$0.57 according to the exchange rate for US$1.
You can't switch back to either once you sign up. \
CJ - You could change??? They refust to let me change. I wanted to change as most stock sites were in US$ and I wanted to manage my exchange by having a different currency but they refused. when did you change? Maybe they just changed it recently.