ICv2 has posted their estimates of the sales by Diamond Comic Distributors to comic stores on the top 25 comic titles in May:

Marvel dominated periodical comic sales in May earning big gains in both dollar and unit market share thanks to a slate that included eight of the top ten best-selling titles. For the second month in a row a Fallen Son: Death of Captain America title was the best-selling title, followed in May by the Steven King-derived Dark Tower: The Gunslinger Born #4. Other Marvel top ten titles included Captain America #26, New Avengers #30, Astonishing X-Men #21, Amazing Spider-Man #540, Mighty Avengers #3 and World War Hulk Prologue, while DC Comics placed Justice League of America #9 in third place and All Star Batman & Robin #5 (originally solicited in the Late Cretaceous) in the ninth spot. DC's Countdown series appears to be off to solid start, but Marvel's World War Hulk titles did even better and it looks like they just might keep the mighty Marvel engine roaring across the next few months.