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	$225.34	11.464%	$251.173	$251.17	$251.15	$251.20
Purchase #2	$19.76	7.817%	$21.3046	$21.30	$21.30	$21.30
Purchase #3	$153.91	13.156%	$174.1584	$174.16	$174.15	$174.20
Purchase #4	$185.60	11.491%	$206.9273	$206.93	$206.95	$206.90
Purchase #5	$184.89	11.651%	$206.4315	$206.43	$206.45	$206.40
Purchase #6	$145.87	13.175%	$165.0884	$165.09	$165.10	$165.10
Purchase #7	$59.67	3.786%	$61.9291	$61.93	$61.95	$61.90
7 purchase totals =	$975.04		$1,087.0123	$1,087.01	$1,087.05	$1,087.00