In Tennessee, a jury has 12 members. That jury must decide the case unanimously, in other words, all twelve have to agree on the verdict. In a civil case, the jury has to decide two issues: first, who is liable or who is at fault, that decision must be unanimous. They also must decide how much the damages are. Again, all twelver jurors must agree on that amount.
If the jury is unable to agree, then the judge can declare a mistrail. If a mistrial is declared, the case can be tried over again by a different jury.