The 5v difference is minimal, and well within the margin your equipment would find acceptable. You should also be careful with the faith you put in your volt meter readings; almost all inexpensive meters will do fine when meassuring a sine wave that is 50-60hz, but when meassuring waves that are modified sines, or waves that have frequencies that are way higher, like the 400hZ the multiwave can put out, they will give unreliable readings.
As said, don't be concerned with 122V, it will work fine and not cause damage.
As said, don't be concerned with 122V, it will work fine and not cause damage.