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	$132.94	7.269%	$142.6034	$142.60	$142.60	$142.60
Purchase #2	$165.87	7.733%	$178.6967	$178.70	$178.70	$178.70
Purchase #3	$64.57	3.599%	$66.8939	$66.89	$66.90	$66.90
Purchase #4	$195.88	13.568%	$222.457	$222.46	$222.45	$222.50
Purchase #5	$37.52	3.176%	$38.7116	$38.71	$38.70	$38.70
Purchase #6	$7.61	8.866%	$8.2847	$8.28	$8.30	$8.30
Purchase #7	$68.61	6.294%	$72.9283	$72.93	$72.95	$72.90
7 purchase totals =	$673.00		$730.5756	$730.57	$730.60	$730.60