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	$153.94	5.630%	$162.6068	$162.61	$162.60	$162.60
Purchase #2	$75.26	3.206%	$77.6728	$77.67	$77.65	$77.70
Purchase #3	$26.86	12.690%	$30.2685	$30.27	$30.25	$30.30
Purchase #4	$247.27	3.690%	$256.3943	$256.39	$256.40	$256.40
Purchase #5	$10.38	13.358%	$11.7666	$11.77	$11.75	$11.80
Purchase #6	$114.57	8.106%	$123.857	$123.86	$123.85	$123.90
Purchase #7	$89.67	12.312%	$100.7102	$100.71	$100.70	$100.70
7 purchase totals =	$717.95		$763.2762	$763.28	$763.20	$763.40