Instead of playing the fifth fret of the E string to be in tune with the A string, play the 7th fret of the E string and unwind the E string (lowering the tuning) so that the sound of it on the 7th fret matches the sound of the open A string. This is dropped D.
If you want to drop all the strings one step, continue from that point to the rest of the strings as you normally would (5th fret = open string under it).