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	$177.86	11.540%	$198.385	$198.39	$198.40	$198.40
Purchase #2	$54.52	12.452%	$61.3088	$61.31	$61.30	$61.30
Purchase #3	$143.27	10.545%	$158.3778	$158.38	$158.40	$158.40
Purchase #4	$234.41	3.308%	$242.1643	$242.16	$242.15	$242.20
Purchase #5	$237.53	6.772%	$253.6155	$253.62	$253.60	$253.60
Purchase #6	$68.93	12.481%	$77.5332	$77.53	$77.55	$77.50
Purchase #7	$17.90	10.400%	$19.7616	$19.76	$19.75	$19.80
7 purchase totals =	$934.42		$1,011.1462	$1,011.15	$1,011.15	$1,011.20