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	$59.47	4.335%	$62.048	$62.05	$62.05	$62.00
Purchase #2	$116.65	13.631%	$132.5506	$132.55	$132.55	$132.60
Purchase #3	$235.74	10.160%	$259.6912	$259.69	$259.70	$259.70
Purchase #4	$165.72	4.256%	$172.773	$172.77	$172.75	$172.80
Purchase #5	$32.89	6.206%	$34.9312	$34.93	$34.95	$34.90
Purchase #6	$144.62	12.618%	$162.8682	$162.87	$162.85	$162.90
Purchase #7	$204.79	9.599%	$224.4478	$224.45	$224.45	$224.40
7 purchase totals =	$959.88		$1,049.3100	$1,049.31	$1,049.30	$1,049.30