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	$91.78	4.196%	$95.6311	$95.63	$95.65	$95.60
Purchase #2	$150.89	3.665%	$156.4201	$156.42	$156.40	$156.40
Purchase #3	$43.57	10.289%	$48.0529	$48.05	$48.05	$48.10
Purchase #4	$205.60	10.812%	$227.8295	$227.83	$227.85	$227.80
Purchase #5	$118.59	5.584%	$125.2121	$125.21	$125.20	$125.20
Purchase #6	$242.88	4.278%	$253.2704	$253.27	$253.25	$253.30
Purchase #7	$217.86	12.669%	$245.4607	$245.46	$245.45	$245.50
7 purchase totals =	$1,071.17		$1,151.8768	$1,151.87	$1,151.85	$1,151.90