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	$191.60	10.646%	$211.9977	$212.00	$212.00	$212.00
Purchase #2	$82.77	7.828%	$89.2492	$89.25	$89.25	$89.20
Purchase #3	$37.60	6.383%	$40	$40.00	$40.00	$40.00
Purchase #4	$157.85	6.730%	$168.4733	$168.47	$168.45	$168.50
Purchase #5	$211.91	9.314%	$231.6473	$231.65	$231.65	$231.60
Purchase #6	$139.70	4.118%	$145.4528	$145.45	$145.45	$145.50
Purchase #7	$132.82	10.266%	$146.4553	$146.46	$146.45	$146.50
7 purchase totals =	$954.25		$1,033.2756	$1,033.28	$1,033.25	$1,033.30