Before:

do 
{
   // Ask whether the user wants to process another student's tuition
   cout << "Would you like to process a student's tuition (y/n)?" << endl; 
   cin >> reply; 
   reply = tolower(reply); 

   // Increment the number of students processed
   ++processed;        
   
} while (!(reply == 'y' || reply == 'n'));