You could use two pins to get a +/-5V signal:
For values > 0 set the positive pin HIGH and the negative pin LOW.
For values < 0 set the positive pin LOW and the negative pin HIGH.
Note that Arduino doesn't have a D/A converter. You will have to use PWM and a low-pass filter to emulate an analog output. Alternatively you could use an external D/A converter.
You should probably use a look-up table for the sine wave.