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	$215.75	4.709%	$225.9097	$225.91	$225.90	$225.90
Purchase #2	$65.25	13.763%	$74.2304	$74.23	$74.25	$74.20
Purchase #3	$151.98	4.246%	$158.4331	$158.43	$158.45	$158.40
Purchase #4	$10.74	13.408%	$12.18	$12.18	$12.20	$12.20
Purchase #5	$238.95	12.517%	$268.8594	$268.86	$268.85	$268.90
Purchase #6	$208.89	6.306%	$222.0626	$222.06	$222.05	$222.10
Purchase #7	$48.90	12.352%	$54.9401	$54.94	$54.95	$54.90
7 purchase totals =	$940.46		$1,016.6153	$1,016.61	$1,016.65	$1,016.60