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	$59.58	4.143%	$62.0484	$62.05	$62.05	$62.00
Purchase #2	$241.76	5.599%	$255.2961	$255.30	$255.30	$255.30
Purchase #3	$71.41	4.431%	$74.5742	$74.57	$74.55	$74.60
Purchase #4	$178.69	3.546%	$185.0263	$185.03	$185.05	$185.00
Purchase #5	$137.76	3.809%	$143.0073	$143.01	$143.00	$143.00
Purchase #6	$55.74	5.711%	$58.9233	$58.92	$58.90	$58.90
Purchase #7	$165.54	11.586%	$184.7195	$184.72	$184.70	$184.70
7 purchase totals =	$910.48		$963.5951	$963.60	$963.55	$963.50