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	$195.93	7.772%	$211.1577	$211.16	$211.15	$211.20
Purchase #2	$190.63	5.171%	$200.4875	$200.49	$200.50	$200.50
Purchase #3	$94.91	11.187%	$105.5276	$105.53	$105.55	$105.50
Purchase #4	$12.81	12.130%	$14.3639	$14.36	$14.35	$14.40
Purchase #5	$19.93	7.395%	$21.4038	$21.40	$21.40	$21.40
Purchase #6	$225.79	5.284%	$237.7207	$237.72	$237.70	$237.70
Purchase #7	$56.42	5.387%	$59.4593	$59.46	$59.45	$59.50
7 purchase totals =	$796.42		$850.1205	$850.12	$850.10	$850.20