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	$69.64	4.748%	$72.9465	$72.95	$72.95	$72.90
Purchase #2	$18.55	11.399%	$20.6645	$20.66	$20.65	$20.70
Purchase #3	$59.91	13.185%	$67.8091	$67.81	$67.80	$67.80
Purchase #4	$133.53	5.415%	$140.7606	$140.76	$140.75	$140.80
Purchase #5	$14.49	5.654%	$15.3093	$15.31	$15.30	$15.30
Purchase #6	$164.40	4.840%	$172.357	$172.36	$172.35	$172.40
Purchase #7	$110.80	5.255%	$116.6225	$116.62	$116.60	$116.60
7 purchase totals =	$571.32		$606.4695	$606.47	$606.40	$606.50