Has an NBA game ever ended 79-76?
Yes. NBA has seen a final score of 79-76 21 times. It first happened on January 3, 1948, when Chicago Stags beat Providence Steamrollers, and most recently on February 8, 2014, when Memphis Grizzlies beat Atlanta Hawks.
That makes 79-76 the 952nd most common final score out of 3,189 that have ever occurred in NBA. One point away, 80-76 has happened 9 times and 79-77 has happened 17 times. At one point the score disappeared for 43 years, between 1953 and 1996.