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	$62.72	13.653%	$71.2832	$71.28	$71.30	$71.30
Purchase #2	$56.98	6.528%	$60.6997	$60.70	$60.70	$60.70
Purchase #3	$29.36	11.415%	$32.7114	$32.71	$32.70	$32.70
Purchase #4	$101.78	10.534%	$112.5015	$112.50	$112.50	$112.50
Purchase #5	$233.46	5.261%	$245.7423	$245.74	$245.75	$245.70
Purchase #6	$224.94	13.804%	$255.9907	$255.99	$256.00	$256.00
Purchase #7	$209.62	13.352%	$237.6085	$237.61	$237.60	$237.60
7 purchase totals =	$918.86		$1,016.5373	$1,016.53	$1,016.55	$1,016.50