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	$231.35	9.559%	$253.4647	$253.46	$253.45	$253.50
Purchase #2	$15.65	5.380%	$16.492	$16.49	$16.50	$16.50
Purchase #3	$210.56	6.176%	$223.5642	$223.56	$223.55	$223.60
Purchase #4	$230.59	9.158%	$251.7074	$251.71	$251.70	$251.70
Purchase #5	$53.95	9.643%	$59.1524	$59.15	$59.15	$59.20
Purchase #6	$159.61	3.854%	$165.7614	$165.76	$165.75	$165.80
Purchase #7	$239.98	5.140%	$252.315	$252.32	$252.30	$252.30
7 purchase totals =	$1,141.69		$1,222.4571	$1,222.45	$1,222.40	$1,222.60