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	$146.98	4.112%	$153.0238	$153.02	$153.00	$153.00
Purchase #2	$151.57	3.691%	$157.1644	$157.16	$157.15	$157.20
Purchase #3	$119.58	7.471%	$128.5138	$128.51	$128.50	$128.50
Purchase #4	$58.93	3.843%	$61.1947	$61.19	$61.20	$61.20
Purchase #5	$99.90	11.766%	$111.6542	$111.65	$111.65	$111.70
Purchase #6	$214.79	3.845%	$223.0487	$223.05	$223.05	$223.00
Purchase #7	$165.85	7.587%	$178.433	$178.43	$178.45	$178.40
7 purchase totals =	$957.60		$1,013.0326	$1,013.01	$1,013.00	$1,013.00