Despite steadily rising gas prices, sales gains held steady across most categories, with Kantar Retail reporting an 8.7% gain in its composite index, which tracks 27 large retailers. Last month the index gained 2.5%, and in April of last year, it gained just 1.2%. For the combined March-April period--an important time frame because of the shift of the Easter holiday--same-store sales rose 5.4% this year, compared to 5.7% in the same two-month period last year.