Rockdale and Conyers residents will soon be able to buy a bottle of wine at the grocery store or a six-pack of beer at the gas station on Sundays after voters approved the Sunday sales referendum Tuesday night. The majority of the county’s Republican voters also went to Newt Gingrich in the presidential preference primary. The Sunday alcohol sales referendum passed with a healthy margin of more than 12 percent in the county, with 56.4 percent voting yes, and more than 14 percent in the city, with 57.1 percent voting yes.