Hi,
You can set Jobroller to accept $ and when a customer pays with english pounds Paypal will convert the pounds to dollars.That's one way to deal with multiple currencies.
If you want to create separate installs that accept different currencies then you can either buy three different domains and install three times WordPress+JobRoller or use a
multisite install which allows you to install multiple themes in one domain using sub domains or sub folders.
Please let me know if you need further assistance.
