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	$85.60	7.390%	$91.9258	$91.93	$91.95	$91.90
Purchase #2	$152.85	10.568%	$169.0032	$169.00	$169.00	$169.00
Purchase #3	$217.32	4.738%	$227.6166	$227.62	$227.60	$227.60
Purchase #4	$89.63	5.840%	$94.8644	$94.86	$94.85	$94.90
Purchase #5	$13.30	9.756%	$14.5975	$14.60	$14.60	$14.60
Purchase #6	$48.27	11.611%	$53.8746	$53.87	$53.85	$53.90
Purchase #7	$206.75	7.179%	$221.5926	$221.59	$221.60	$221.60
7 purchase totals =	$813.72		$873.4747	$873.47	$873.45	$873.50