Last year, Cayman Corporation had sales of $$6$ million, total variable costs of $$2$ million, and total fixed costs of $$1$ million. In addition, they paid $$480,000$ in interest to bondholders. Cayman has a $21\%$ marginal tax rate. If Cayman's sales increase $5\%,$ what should be the increase in operating income? $($Should be a percentage$)$