I have never used round in a directional sense, it is always around. The Americans that use round in that way usually also say y'all and have a twangy accent. Also, the appostrophe before it shows that you're leaving off a letter (just like goin') so it's not normal nor is it proper english.
People slur their words when speaking all the time. No one says something to exact pronunciation every time. That would be exhausting and robotic. When speaking informal English, people tend to drop the 'g' and simply enunciate the verb and 'in'. Writing informal verbs in English would require you to drop the letter and add the apostrophe. It is used in many classics and modern speech. "Round" and/or "Goin'" are not typically part of the southern dialect. They are slurred words for informal usage.