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	$195.87	7.379%	$210.3232	$210.32	$210.30	$210.30
Purchase #2	$184.97	5.830%	$195.7538	$195.75	$195.75	$195.80
Purchase #3	$168.89	6.152%	$179.2801	$179.28	$179.30	$179.30
Purchase #4	$152.30	4.601%	$159.3073	$159.31	$159.30	$159.30
Purchase #5	$164.60	3.771%	$170.8071	$170.81	$170.80	$170.80
Purchase #6	$54.47	13.240%	$61.6818	$61.68	$61.70	$61.70
Purchase #7	$168.37	10.287%	$185.6902	$185.69	$185.70	$185.70
7 purchase totals =	$1,089.47		$1,162.8435	$1,162.84	$1,162.85	$1,162.90