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	$83.45	13.768%	$94.9394	$94.94	$94.95	$94.90
Purchase #2	$143.57	10.236%	$158.2658	$158.27	$158.25	$158.30
Purchase #3	$169.80	8.721%	$184.6083	$184.61	$184.60	$184.60
Purchase #4	$129.54	11.450%	$144.3723	$144.37	$144.35	$144.40
Purchase #5	$217.87	10.108%	$239.8923	$239.89	$239.90	$239.90
Purchase #6	$50.88	5.700%	$53.7802	$53.78	$53.80	$53.80
Purchase #7	$169.26	11.762%	$189.1684	$189.17	$189.15	$189.20
7 purchase totals =	$964.37		$1,065.0267	$1,065.03	$1,065.00	$1,065.10