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	$223.72	9.451%	$244.8638	$244.86	$244.85	$244.90
Purchase #2	$13.33	11.405%	$14.8503	$14.85	$14.85	$14.90
Purchase #3	$33.81	6.124%	$35.8805	$35.88	$35.90	$35.90
Purchase #4	$95.78	10.708%	$106.0361	$106.04	$106.05	$106.00
Purchase #5	$187.42	13.313%	$212.3712	$212.37	$212.35	$212.40
Purchase #6	$236.74	7.831%	$255.2791	$255.28	$255.30	$255.30
Purchase #7	$248.90	12.816%	$280.799	$280.80	$280.80	$280.80
7 purchase totals =	$1,039.70		$1,150.0800	$1,150.08	$1,150.10	$1,150.20