Hi Judy,
Proper tuning of a piano takes much more than using an electronic tuner. If one were to tune every string on the piano to exact pitch, it would sound horrible. A good piano technician/tuner will impart subtle characteristics to the tuning of every piano string, ergo, a couple of cents - plus/minus off in the tuning. A real pipe organ is tuned the old-fashioned way - the only way - by ear.
Cheers,
Corno Dolce