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	$45.99	5.695%	$48.6091	$48.61	$48.60	$48.60
Purchase #2	$7.80	13.513%	$8.854	$8.85	$8.85	$8.90
Purchase #3	$95.45	5.239%	$100.4506	$100.45	$100.45	$100.50
Purchase #4	$224.28	5.455%	$236.5145	$236.51	$236.50	$236.50
Purchase #5	$247.39	13.330%	$280.3671	$280.37	$280.35	$280.40
Purchase #6	$249.80	9.456%	$273.4211	$273.42	$273.40	$273.40
Purchase #7	$102.41	12.510%	$115.2215	$115.22	$115.20	$115.20
7 purchase totals =	$973.12		$1,063.4379	$1,063.43	$1,063.35	$1,063.50