A machine shop has a credit card that offers rebates on purchases. At the end of May, the company had a credit card bill of $$18,471\mathrm{.}29.$ If the company must make a minimum payment that is the greater of $$500$ or $4\mathrm{.}5\%$ of the credit card bill, what is the minimum monthly payment for May? $($Round your answer to the nearest cent.$)$