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	$85.87	10.280%	$94.6974	$94.70	$94.70	$94.70
Purchase #2	$92.49	13.287%	$104.7791	$104.78	$104.80	$104.80
Purchase #3	$100.49	10.528%	$111.0696	$111.07	$111.05	$111.10
Purchase #4	$148.30	13.785%	$168.7432	$168.74	$168.75	$168.70
Purchase #5	$230.84	10.673%	$255.4776	$255.48	$255.50	$255.50
Purchase #6	$175.39	11.208%	$195.0477	$195.05	$195.05	$195.00
Purchase #7	$88.59	3.584%	$91.7651	$91.77	$91.75	$91.80
7 purchase totals =	$921.97		$1,021.5797	$1,021.59	$1,021.60	$1,021.60