I just purchased a nice little Sperry DSA-500 multimeter at Home Depot for $49.00. It seems to work just fine. However, it is not a true rms multimeter. Will it still measure voltage accurately?

Depends on what sort of accuracy you require.
Any non-TrueRMS meter will test the Average voltage (as in 63.7% of the peak voltage) as opposed to 70.7% (RMS).

I just need it to test voltage drop at the outlet, neutral-ground voltage etc.

By rights, there should be no voltage between these conductors.
I could be wrong too.
Frank,
A T-RMS meter is only of value to those that measure voltages with lots of harmonics on the supply.
The average electrician doesn't need to worry , I have one, but I wouldn't recommend every guy runs out and gets one.
My Fluke 80 does just as gooder job and why spend good cash when you don't have to?.