Reading a 3-axis hall sensor

I have a project at work that involves taking some hall sensor measurements.  The sensor we bought outputs 3 analog signals, one for each axis.  Depending on the direction of the magnetic field lines, the analog output voltages will either be positive or negative.  The sensor is calibrated to output 5V per Tesla.  We will only be measuring up to maybe 1.2T.

The part I'm stuck on is how would I go about digitizing the positive/negative voltage values?  I assume an ADC is involved but I can't find anything that will read a negative voltage.  Any insight on where to start?