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	$165.59	5.774%	$175.1512	$175.15	$175.15	$175.20
Purchase #2	$26.25	4.366%	$27.3961	$27.40	$27.40	$27.40
Purchase #3	$68.29	6.304%	$72.595	$72.60	$72.60	$72.60
Purchase #4	$223.61	8.235%	$242.0243	$242.02	$242.00	$242.00
Purchase #5	$38.60	3.849%	$40.0857	$40.09	$40.10	$40.10
Purchase #6	$108.94	4.768%	$114.1343	$114.13	$114.15	$114.10
Purchase #7	$231.48	10.521%	$255.834	$255.83	$255.85	$255.80
7 purchase totals =	$862.76		$927.2206	$927.22	$927.25	$927.20