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	$206.63	3.794%	$214.4695	$214.47	$214.45	$214.50
Purchase #2	$55.38	6.691%	$59.0855	$59.09	$59.10	$59.10
Purchase #3	$195.61	10.159%	$215.482	$215.48	$215.50	$215.50
Purchase #4	$160.36	5.444%	$169.09	$169.09	$169.10	$169.10
Purchase #5	$118.92	3.840%	$123.4865	$123.49	$123.50	$123.50
Purchase #6	$30.91	7.618%	$33.2647	$33.26	$33.25	$33.30
Purchase #7	$235.96	4.548%	$246.6915	$246.69	$246.70	$246.70
7 purchase totals =	$1,003.77		$1,061.5697	$1,061.57	$1,061.60	$1,061.70