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	$90.50	5.495%	$95.473	$95.47	$95.45	$95.50
Purchase #2	$59.75	13.173%	$67.6209	$67.62	$67.60	$67.60
Purchase #3	$161.29	11.571%	$179.9529	$179.95	$179.95	$180.00
Purchase #4	$40.57	8.245%	$43.915	$43.92	$43.90	$43.90
Purchase #5	$206.69	7.639%	$222.479	$222.48	$222.50	$222.50
Purchase #6	$68.97	10.349%	$76.1077	$76.11	$76.10	$76.10
Purchase #7	$105.42	5.634%	$111.3594	$111.36	$111.35	$111.40
7 purchase totals =	$733.19		$796.9079	$796.91	$796.85	$797.00