int tmp = score/10;
if(tmp > 10)
    tmp = 10;
switch(tmp)
{
   case 0: 
   case 1:
   case 2:
   case 3:
   case 4:
   case 5: // code of score < 60 && score >= 0
               break;
   case 6: // code of score <70 && score >=60
               break;
   case 7: // code of score < 80 && score >= 70
               break;
   case 8: // code of score < 90 && score >= 80
               break;
   case 9: // code of score < 100 && score >= 90
               break;
   case 10: // code of score >= 100
               break;
   default: // code of exception case
}