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	$217.98	4.413%	$227.5995	$227.60	$227.60	$227.60
Purchase #2	$50.31	4.244%	$52.4452	$52.45	$52.45	$52.40
Purchase #3	$62.70	4.117%	$65.2814	$65.28	$65.30	$65.30
Purchase #4	$46.79	4.547%	$48.9175	$48.92	$48.90	$48.90
Purchase #5	$80.41	6.301%	$85.4766	$85.48	$85.50	$85.50
Purchase #6	$104.40	12.567%	$117.5199	$117.52	$117.50	$117.50
Purchase #7	$120.50	10.735%	$133.4357	$133.44	$133.45	$133.40
7 purchase totals =	$683.09		$730.6758	$730.69	$730.70	$730.60