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	10.845%	$95.1826	$95.18	$95.20	$95.20
Purchase #2	$63.26	13.557%	$71.8362	$71.84	$71.85	$71.80
Purchase #3	$133.38	5.758%	$141.06	$141.06	$141.05	$141.10
Purchase #4	$92.70	13.176%	$104.9142	$104.91	$104.90	$104.90
Purchase #5	$122.31	8.182%	$132.3174	$132.32	$132.30	$132.30
Purchase #6	$230.49	4.360%	$240.5394	$240.54	$240.55	$240.50
Purchase #7	$73.31	7.411%	$78.743	$78.74	$78.75	$78.70
7 purchase totals =	$801.32		$864.5928	$864.59	$864.60	$864.50