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	$85.92	10.143%	$94.6349	$94.63	$94.65	$94.60
Purchase #2	$163.58	13.262%	$185.274	$185.27	$185.25	$185.30
Purchase #3	$97.48	3.437%	$100.8304	$100.83	$100.85	$100.80
Purchase #4	$45.74	4.466%	$47.7827	$47.78	$47.80	$47.80
Purchase #5	$36.75	6.204%	$39.03	$39.03	$39.05	$39.00
Purchase #6	$190.49	3.288%	$196.7533	$196.75	$196.75	$196.80
Purchase #7	$132.43	13.352%	$150.1121	$150.11	$150.10	$150.10
7 purchase totals =	$752.39		$814.4174	$814.40	$814.45	$814.40