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	$95.83	3.444%	$99.1304	$99.13	$99.15	$99.10
Purchase #2	$26.90	11.293%	$29.9378	$29.94	$29.95	$29.90
Purchase #3	$177.74	10.666%	$196.6977	$196.70	$196.70	$196.70
Purchase #4	$184.32	6.846%	$196.9385	$196.94	$196.95	$196.90
Purchase #5	$137.30	5.103%	$144.3064	$144.31	$144.30	$144.30
Purchase #6	$85.74	8.319%	$92.8727	$92.87	$92.85	$92.90
Purchase #7	$243.66	5.185%	$256.2938	$256.29	$256.30	$256.30
7 purchase totals =	$951.49		$1,016.1773	$1,016.18	$1,016.20	$1,016.10