TOP PERFORMERS Pepsi Coca-Cola Mountain Dew (PepsiCo) HONORABLE MENTIONS Dr Pepper (Dr Pepper Snapple Group) Sprite (Coca-Cola Co.) Carbonated soft drink sales may be slowing a bit, but they still dominate convenience store coolers. Chalk it up to brand-loyal buyers or market saturation, but one thing is certain: This is a packaged beverage segment retailers…