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	$196.53	5.403%	$207.1485	$207.15	$207.15	$207.10
Purchase #2	$57.29	10.395%	$63.2453	$63.25	$63.25	$63.20
Purchase #3	$28.29	12.330%	$31.7782	$31.78	$31.80	$31.80
Purchase #4	$168.49	3.545%	$174.463	$174.46	$174.45	$174.50
Purchase #5	$166.60	3.517%	$172.4593	$172.46	$172.45	$172.50
Purchase #6	$27.52	8.528%	$29.8669	$29.87	$29.85	$29.90
Purchase #7	$19.86	10.140%	$21.8738	$21.87	$21.85	$21.90
7 purchase totals =	$664.58		$700.8350	$700.84	$700.80	$700.90