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	$63.95	13.542%	$72.6101	$72.61	$72.60	$72.60
Purchase #2	$74.29	5.207%	$78.1583	$78.16	$78.15	$78.20
Purchase #3	$151.96	13.602%	$172.6296	$172.63	$172.65	$172.60
Purchase #4	$12.90	3.557%	$13.3589	$13.36	$13.35	$13.40
Purchase #5	$205.54	9.217%	$224.4846	$224.48	$224.50	$224.50
Purchase #6	$146.57	6.703%	$156.3946	$156.39	$156.40	$156.40
Purchase #7	$230.27	6.314%	$244.8092	$244.81	$244.80	$244.80
7 purchase totals =	$885.48		$962.4453	$962.44	$962.45	$962.50