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	$41.95	11.689%	$46.8535	$46.85	$46.85	$46.90
Purchase #2	$204.45	3.195%	$210.9822	$210.98	$211.00	$211.00
Purchase #3	$54.66	8.181%	$59.1317	$59.13	$59.15	$59.10
Purchase #4	$11.26	8.509%	$12.2181	$12.22	$12.20	$12.20
Purchase #5	$90.97	7.443%	$97.7409	$97.74	$97.75	$97.70
Purchase #6	$234.54	8.659%	$254.8488	$254.85	$254.85	$254.80
Purchase #7	$45.34	3.290%	$46.8317	$46.83	$46.85	$46.80
7 purchase totals =	$683.17		$728.6069	$728.60	$728.65	$728.50