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	$232.82	12.654%	$262.281	$262.28	$262.30	$262.30
Purchase #2	$70.32	9.339%	$76.8872	$76.89	$76.90	$76.90
Purchase #3	$143.33	5.649%	$151.4267	$151.43	$151.45	$151.40
Purchase #4	$225.89	13.405%	$256.1706	$256.17	$256.15	$256.20
Purchase #5	$186.55	3.483%	$193.0475	$193.05	$193.05	$193.00
Purchase #6	$239.83	7.810%	$258.5607	$258.56	$258.55	$258.60
Purchase #7	$238.97	4.233%	$249.0856	$249.09	$249.10	$249.10
7 purchase totals =	$1,337.71		$1,447.4593	$1,447.47	$1,447.50	$1,447.50