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	$38.65	13.743%	$43.9617	$43.96	$43.95	$44.00
Purchase #2	$172.83	10.451%	$190.8925	$190.89	$190.90	$190.90
Purchase #3	$205.27	4.622%	$214.7576	$214.76	$214.75	$214.80
Purchase #4	$56.66	10.638%	$62.6875	$62.69	$62.70	$62.70
Purchase #5	$196.56	3.830%	$204.0882	$204.09	$204.10	$204.10
Purchase #6	$248.80	13.292%	$281.8705	$281.87	$281.85	$281.90
Purchase #7	$59.92	12.162%	$67.2075	$67.21	$67.20	$67.20
7 purchase totals =	$978.69		$1,065.4655	$1,065.47	$1,065.45	$1,065.60