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	$59.52	3.243%	$61.4502	$61.45	$61.45	$61.50
Purchase #2	$76.33	4.162%	$79.5069	$79.51	$79.50	$79.50
Purchase #3	$172.39	3.738%	$178.8339	$178.83	$178.85	$178.80
Purchase #4	$47.54	9.195%	$51.9113	$51.91	$51.90	$51.90
Purchase #5	$129.91	9.843%	$142.697	$142.70	$142.70	$142.70
Purchase #6	$122.63	13.769%	$139.5149	$139.51	$139.50	$139.50
Purchase #7	$125.66	9.429%	$137.5085	$137.51	$137.50	$137.50
7 purchase totals =	$733.98		$791.4227	$791.42	$791.40	$791.40