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	$182.38	4.526%	$190.6345	$190.63	$190.65	$190.60
Purchase #2	$206.29	8.153%	$223.1088	$223.11	$223.10	$223.10
Purchase #3	$83.58	6.328%	$88.8689	$88.87	$88.85	$88.90
Purchase #4	$152.56	4.421%	$159.3047	$159.30	$159.30	$159.30
Purchase #5	$191.41	13.800%	$217.8246	$217.82	$217.80	$217.80
Purchase #6	$105.81	6.433%	$112.6168	$112.62	$112.60	$112.60
Purchase #7	$95.67	10.468%	$105.6847	$105.68	$105.70	$105.70
7 purchase totals =	$1,017.70		$1,098.0430	$1,098.03	$1,098.00	$1,098.00