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	$60.34	3.735%	$62.5937	$62.59	$62.60	$62.60
Purchase #2	$214.25	8.853%	$233.2176	$233.22	$233.20	$233.20
Purchase #3	$13.30	13.314%	$15.0708	$15.07	$15.05	$15.10
Purchase #4	$38.94	12.379%	$43.7604	$43.76	$43.75	$43.80
Purchase #5	$39.83	10.177%	$43.8835	$43.88	$43.90	$43.90
Purchase #6	$226.25	13.431%	$256.6376	$256.64	$256.65	$256.60
Purchase #7	$40.66	3.732%	$42.1774	$42.18	$42.20	$42.20
7 purchase totals =	$633.57		$697.3410	$697.34	$697.35	$697.40