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	$57.35	8.637%	$62.3033	$62.30	$62.30	$62.30
Purchase #2	$247.25	13.250%	$280.0106	$280.01	$280.00	$280.00
Purchase #3	$95.64	5.151%	$100.5664	$100.57	$100.55	$100.60
Purchase #4	$34.47	11.311%	$38.3689	$38.37	$38.35	$38.40
Purchase #5	$170.61	5.182%	$179.451	$179.45	$179.45	$179.50
Purchase #6	$224.44	5.176%	$236.057	$236.06	$236.05	$236.10
Purchase #7	$200.83	4.153%	$209.1705	$209.17	$209.15	$209.20
7 purchase totals =	$1,030.59		$1,105.9277	$1,105.93	$1,105.85	$1,106.10