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	$140.80	9.826%	$154.635	$154.64	$154.65	$154.60
Purchase #2	$234.82	7.197%	$251.72	$251.72	$251.70	$251.70
Purchase #3	$187.26	6.850%	$200.0873	$200.09	$200.10	$200.10
Purchase #4	$142.46	11.439%	$158.756	$158.76	$158.75	$158.80
Purchase #5	$108.45	7.620%	$116.7139	$116.71	$116.70	$116.70
Purchase #6	$99.55	11.540%	$111.0381	$111.04	$111.05	$111.00
Purchase #7	$151.52	3.189%	$156.352	$156.35	$156.35	$156.40
7 purchase totals =	$1,064.86		$1,149.3023	$1,149.31	$1,149.30	$1,149.30