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	$94.41	8.491%	$102.4264	$102.43	$102.45	$102.40
Purchase #2	$59.86	10.699%	$66.2644	$66.26	$66.25	$66.30
Purchase #3	$195.74	13.338%	$221.8478	$221.85	$221.85	$221.80
Purchase #4	$227.78	8.685%	$247.5627	$247.56	$247.55	$247.60
Purchase #5	$60.29	6.740%	$64.3535	$64.35	$64.35	$64.40
Purchase #6	$238.96	12.859%	$269.6879	$269.69	$269.70	$269.70
Purchase #7	$82.51	8.389%	$89.4318	$89.43	$89.45	$89.40
7 purchase totals =	$959.55		$1,061.5745	$1,061.57	$1,061.60	$1,061.60