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	$213.99	6.567%	$228.0427	$228.04	$228.05	$228.00
Purchase #2	$237.81	13.117%	$269.0035	$269.00	$269.00	$269.00
Purchase #3	$56.82	4.591%	$59.4286	$59.43	$59.45	$59.40
Purchase #4	$44.50	8.866%	$48.4454	$48.45	$48.45	$48.40
Purchase #5	$59.38	11.628%	$66.2847	$66.28	$66.30	$66.30
Purchase #6	$10.42	10.402%	$11.5039	$11.50	$11.50	$11.50
Purchase #7	$128.58	12.534%	$144.6962	$144.70	$144.70	$144.70
7 purchase totals =	$751.50		$827.4050	$827.40	$827.45	$827.30