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	$87.59	9.225%	$95.6702	$95.67	$95.65	$95.70
Purchase #2	$46.40	9.614%	$50.8609	$50.86	$50.85	$50.90
Purchase #3	$10.50	12.357%	$11.7975	$11.80	$11.80	$11.80
Purchase #4	$11.94	8.139%	$12.9118	$12.91	$12.90	$12.90
Purchase #5	$126.85	13.366%	$143.8048	$143.80	$143.80	$143.80
Purchase #6	$186.38	10.686%	$206.2966	$206.30	$206.30	$206.30
Purchase #7	$10.66	7.568%	$11.4667	$11.47	$11.45	$11.50
7 purchase totals =	$480.32		$532.8085	$532.81	$532.75	$532.90