Custom Tap Handles In Ireland, Is It A Custom To Tap Three Times On A Man's Coffin During His Funeral, If So Why?

In Ireland, is it a custom to tap three times on a man's coffin during his funeral, if so why? - custom tap handles

My father died at the funeral and touched the coffin inexpilcably me three times with his finger. Is this common in Ireland and if so, what is the reason, again in him? Sean Keegan