Dynamic dispatch is only used when using pointers, not with class values:

  Employee e1("Bob", 45000.00);
  Manager m1("Alex", 60000.00);

 // No dynamic dispatch here. Employee's getBonus is used
  e1 = m1;
  cout << e1.getBonus() << endl;  

  Employee *ep1 = new Employee("Bob", 45000.00);
  Manager *mp1 = new Employee("Alex", 60000.00);

 // Dynamic dispatch here since (a) pointers are used
 // and (b) the getBonus function is 'virtual'.
 // So Manager's getBonus is used since ep1 points to
 // a Manager object
  ep1 = mp1;
  cout << ep1->getBonus() << endl;