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	$207.77	3.387%	$214.8072	$214.81	$214.80	$214.80
Purchase #2	$223.43	4.792%	$234.1368	$234.14	$234.15	$234.10
Purchase #3	$41.75	3.832%	$43.3499	$43.35	$43.35	$43.30
Purchase #4	$218.83	11.457%	$243.9014	$243.90	$243.90	$243.90
Purchase #5	$58.39	3.230%	$60.276	$60.28	$60.30	$60.30
Purchase #6	$128.85	12.436%	$144.8738	$144.87	$144.85	$144.90
Purchase #7	$122.74	3.772%	$127.3698	$127.37	$127.35	$127.40
7 purchase totals =	$1,001.76		$1,068.7149	$1,068.72	$1,068.70	$1,068.70