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	$214.40	4.119%	$223.2311	$223.23	$223.25	$223.20
Purchase #2	$196.50	13.156%	$222.3515	$222.35	$222.35	$222.40
Purchase #3	$47.46	3.723%	$49.2269	$49.23	$49.25	$49.20
Purchase #4	$168.55	11.870%	$188.5569	$188.56	$188.55	$188.60
Purchase #5	$150.53	8.396%	$163.1685	$163.17	$163.15	$163.20
Purchase #6	$105.30	13.461%	$119.4744	$119.47	$119.45	$119.50
Purchase #7	$169.60	9.468%	$185.6577	$185.66	$185.65	$185.70
7 purchase totals =	$1,052.34		$1,151.6670	$1,151.67	$1,151.65	$1,151.80