The top-tied bestselling books of all time are the Bible and Quotations from Chairman Mao, each at about 6 billion published copies apiece. It's a great shame that, realistically, there's no reliable way to separate the two chart-toppers by discounting copies bought or kept purely to evade the adverse consequences of being discovered not to have one - if there were, one suspects that the Holy Qu'ran might not have made it into the top three, either.
Also included in Publishing Perspectives's 'Top 25' are books by J.R.R. Tolkien and C.S. Lewis; Lew Wallace's Ben Hur: A Tale of the Christ, thought to have sold c.50 million copies, closely failed to make the list[1].