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	$214.66	11.460%	$239.26	$239.26	$239.25	$239.30
Purchase #2	$194.25	8.182%	$210.1435	$210.14	$210.15	$210.10
Purchase #3	$233.64	9.303%	$255.3755	$255.38	$255.40	$255.40
Purchase #4	$164.29	5.201%	$172.8347	$172.83	$172.85	$172.80
Purchase #5	$57.52	4.125%	$59.8927	$59.89	$59.90	$59.90
Purchase #6	$159.49	8.857%	$173.616	$173.62	$173.60	$173.60
Purchase #7	$59.76	10.401%	$65.9756	$65.98	$66.00	$66.00
7 purchase totals =	$1,083.61		$1,177.0980	$1,177.10	$1,177.15	$1,177.10