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	$116.92	9.265%	$127.7526	$127.75	$127.75	$127.80
Purchase #2	$96.61	8.340%	$104.6673	$104.67	$104.65	$104.70
Purchase #3	$136.54	8.821%	$148.5842	$148.58	$148.60	$148.60
Purchase #4	$40.80	4.822%	$42.7674	$42.77	$42.75	$42.80
Purchase #5	$217.76	4.444%	$227.4373	$227.44	$227.45	$227.40
Purchase #6	$84.92	12.711%	$95.7142	$95.71	$95.70	$95.70
Purchase #7	$248.39	6.874%	$265.4643	$265.46	$265.45	$265.50
7 purchase totals =	$941.94		$1,012.3873	$1,012.38	$1,012.35	$1,012.50