Katy Perry's "Roar" tops the 5 million mark in digital sales this week. It's her fifth song to reach that plateau. This extends her lead as the artist with the most 5-million-sellers in digital history. Lady Gaga is the runner-up with three. Perry's other 5 million-sellers are "Firework" (6,545,000), "E.T." (featuring Kanye West, 5,700,000), "California Gurls," featuring Snoop Dogg, 5,604,000) and "Hot N' Cold" (5,486,000).
