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	$192.50	11.525%	$214.6856	$214.69	$214.70	$214.70
Purchase #2	$243.25	12.268%	$273.0919	$273.09	$273.10	$273.10
Purchase #3	$92.51	5.451%	$97.5527	$97.55	$97.55	$97.60
Purchase #4	$201.48	4.163%	$209.8676	$209.87	$209.85	$209.90
Purchase #5	$120.77	5.646%	$127.5887	$127.59	$127.60	$127.60
Purchase #6	$98.66	10.343%	$108.8644	$108.86	$108.85	$108.90
Purchase #7	$21.73	11.568%	$24.2437	$24.24	$24.25	$24.20
7 purchase totals =	$970.90		$1,055.8946	$1,055.89	$1,055.90	$1,056.00