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	$184.75	8.403%	$200.2745	$200.27	$200.25	$200.30
Purchase #2	$229.30	13.507%	$260.2716	$260.27	$260.25	$260.30
Purchase #3	$165.84	5.856%	$175.5516	$175.55	$175.55	$175.60
Purchase #4	$241.81	6.614%	$257.8033	$257.80	$257.80	$257.80
Purchase #5	$55.28	7.618%	$59.4912	$59.49	$59.50	$59.50
Purchase #6	$173.49	10.418%	$191.5642	$191.56	$191.55	$191.60
Purchase #7	$192.66	11.377%	$214.5789	$214.58	$214.60	$214.60
7 purchase totals =	$1,243.13		$1,359.5353	$1,359.52	$1,359.50	$1,359.70