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	$57.31	8.719%	$62.3069	$62.31	$62.30	$62.30
Purchase #2	$149.42	8.344%	$161.8876	$161.89	$161.90	$161.90
Purchase #3	$172.88	4.523%	$180.6994	$180.70	$180.70	$180.70
Purchase #4	$61.97	5.327%	$65.2711	$65.27	$65.25	$65.30
Purchase #5	$74.96	3.369%	$77.4854	$77.49	$77.50	$77.50
Purchase #6	$117.89	11.844%	$131.8529	$131.85	$131.85	$131.90
Purchase #7	$41.70	11.774%	$46.6098	$46.61	$46.60	$46.60
7 purchase totals =	$676.13		$726.1131	$726.12	$726.10	$726.20