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	$95.69	13.662%	$108.7632	$108.76	$108.75	$108.80
Purchase #2	$14.82	11.223%	$16.4832	$16.48	$16.50	$16.50
Purchase #3	$67.85	5.314%	$71.4555	$71.46	$71.45	$71.50
Purchase #4	$78.70	13.509%	$89.3316	$89.33	$89.35	$89.30
Purchase #5	$22.84	4.295%	$23.821	$23.82	$23.80	$23.80
Purchase #6	$16.85	8.383%	$18.2625	$18.26	$18.25	$18.30
Purchase #7	$169.38	4.146%	$176.4025	$176.40	$176.40	$176.40
7 purchase totals =	$466.13		$504.5195	$504.51	$504.50	$504.60