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	$175.66	11.307%	$195.5219	$195.52	$195.50	$195.50
Purchase #2	$70.52	10.664%	$78.0403	$78.04	$78.05	$78.00
Purchase #3	$244.82	4.404%	$255.6019	$255.60	$255.60	$255.60
Purchase #4	$5.30	5.579%	$5.5957	$5.60	$5.60	$5.60
Purchase #5	$156.29	8.395%	$169.4105	$169.41	$169.40	$169.40
Purchase #6	$51.45	6.386%	$54.7356	$54.74	$54.75	$54.70
Purchase #7	$51.66	6.796%	$55.1708	$55.17	$55.15	$55.20
7 purchase totals =	$755.70		$814.0767	$814.08	$814.05	$814.00