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	$85.56	10.518%	$94.5592	$94.56	$94.55	$94.60
Purchase #2	$65.45	10.356%	$72.228	$72.23	$72.25	$72.20
Purchase #3	$143.75	4.411%	$150.0908	$150.09	$150.10	$150.10
Purchase #4	$11.93	10.208%	$13.1478	$13.15	$13.15	$13.10
Purchase #5	$52.64	11.750%	$58.8252	$58.83	$58.85	$58.80
Purchase #6	$61.89	7.161%	$66.3219	$66.32	$66.30	$66.30
Purchase #7	$76.47	7.801%	$82.4354	$82.44	$82.45	$82.40
7 purchase totals =	$497.69		$537.6083	$537.62	$537.65	$537.50