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	$211.42	6.865%	$225.934	$225.93	$225.95	$225.90
Purchase #2	$72.77	7.310%	$78.0895	$78.09	$78.10	$78.10
Purchase #3	$77.77	8.828%	$84.6355	$84.64	$84.65	$84.60
Purchase #4	$239.69	9.340%	$262.077	$262.08	$262.10	$262.10
Purchase #5	$137.89	10.867%	$152.8745	$152.87	$152.85	$152.90
Purchase #6	$151.51	4.679%	$158.5992	$158.60	$158.60	$158.60
Purchase #7	$109.77	13.495%	$124.5835	$124.58	$124.60	$124.60
7 purchase totals =	$1,000.82		$1,086.7932	$1,086.79	$1,086.85	$1,086.80