Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$55.97	11.466%	$62.3875	$62.39	$62.40	$62.40
Purchase #2	$12.54	10.583%	$13.8671	$13.87	$13.85	$13.90
Purchase #3	$87.54	4.578%	$91.5476	$91.55	$91.55	$91.50
Purchase #4	$63.90	3.223%	$65.9595	$65.96	$65.95	$66.00
Purchase #5	$218.90	12.129%	$245.4504	$245.45	$245.45	$245.50
Purchase #6	$74.53	5.373%	$78.5345	$78.53	$78.55	$78.50
Purchase #7	$161.98	11.233%	$180.1752	$180.18	$180.20	$180.20
7 purchase totals =	$675.36		$737.9218	$737.93	$737.95	$738.00