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	$175.82	11.205%	$195.5206	$195.52	$195.50	$195.50
Purchase #2	$83.49	3.786%	$86.6509	$86.65	$86.65	$86.70
Purchase #3	$145.97	3.457%	$151.0162	$151.02	$151.00	$151.00
Purchase #4	$72.67	5.509%	$76.6734	$76.67	$76.65	$76.70
Purchase #5	$129.57	11.646%	$144.6597	$144.66	$144.65	$144.70
Purchase #6	$57.57	3.831%	$59.7755	$59.78	$59.80	$59.80
Purchase #7	$142.61	8.334%	$154.4951	$154.50	$154.50	$154.50
7 purchase totals =	$807.70		$868.7914	$868.80	$868.75	$868.90