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	$88.67	7.594%	$95.4036	$95.40	$95.40	$95.40
Purchase #2	$182.99	11.761%	$204.5115	$204.51	$204.50	$204.50
Purchase #3	$245.75	9.679%	$269.5361	$269.54	$269.55	$269.50
Purchase #4	$65.81	8.433%	$71.3598	$71.36	$71.35	$71.40
Purchase #5	$59.75	10.284%	$65.8947	$65.89	$65.90	$65.90
Purchase #6	$54.29	11.397%	$60.4774	$60.48	$60.50	$60.50
Purchase #7	$34.46	11.656%	$38.4767	$38.48	$38.50	$38.50
7 purchase totals =	$731.72		$805.6598	$805.66	$805.70	$805.70