I guess it depends on how you judge the statistics available and the interpretation of your question, but according to the Recording Industry Association of America (RIAA), rock still rules. The Beatles are the all-time leader in certified album sales in the United States with more than 177 million albums sold. Of course, The Beatles are not native-born Americans, so the top-selling American music artist in certified album sales is Elvis Presley, with 134.5 million units sold. Rounding out the Top Ten are Garth Brooks, Led Zeppelin, The Eagles, Billy Joel, Pink Floyd, Barbra Streisand, AC/DC and Elton John. Michael Jackson ranks 11th. Note that the RIAA began its certification process in 1958; otherwise, Bing Crosby would almost certainly have cracked this list, as well as Frank Sinatra.
According to Wikipedia, the top sellers are The Beatles, Elvis Presley, Michael Jackson, Madonna, Elton John, Led Zeppelin and Queen. In total worldwide sales, Elvis surpasses The Beatles with more than 1 billion album sales, followed by Michael Jackson, Frank Sinatra, Abba and Led Zeppelin.