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	$154.48	5.463%	$162.9192	$162.92	$162.90	$162.90
Purchase #2	$140.60	4.476%	$146.8933	$146.89	$146.90	$146.90
Purchase #3	$90.50	11.324%	$100.7482	$100.75	$100.75	$100.70
Purchase #4	$171.42	13.613%	$194.7554	$194.76	$194.75	$194.80
Purchase #5	$32.95	12.268%	$36.9923	$36.99	$37.00	$37.00
Purchase #6	$110.30	3.797%	$114.4881	$114.49	$114.50	$114.50
Purchase #7	$240.91	6.465%	$256.4848	$256.48	$256.50	$256.50
7 purchase totals =	$941.16		$1,013.2813	$1,013.28	$1,013.30	$1,013.30