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	$54.86	11.256%	$61.035	$61.04	$61.05	$61.00
Purchase #2	$105.37	7.132%	$112.885	$112.89	$112.90	$112.90
Purchase #3	$48.82	11.443%	$54.4065	$54.41	$54.40	$54.40
Purchase #4	$46.67	4.783%	$48.9022	$48.90	$48.90	$48.90
Purchase #5	$249.68	11.605%	$278.6554	$278.66	$278.65	$278.70
Purchase #6	$40.58	3.361%	$41.9439	$41.94	$41.95	$41.90
Purchase #7	$118.47	5.507%	$124.9941	$124.99	$125.00	$125.00
7 purchase totals =	$664.45		$722.8221	$722.83	$722.85	$722.80