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	$57.60	9.314%	$62.9649	$62.96	$62.95	$63.00
Purchase #2	$236.30	13.309%	$267.7492	$267.75	$267.75	$267.70
Purchase #3	$34.31	8.777%	$37.3214	$37.32	$37.30	$37.30
Purchase #4	$122.43	4.164%	$127.528	$127.53	$127.55	$127.50
Purchase #5	$12.98	12.833%	$14.6457	$14.65	$14.65	$14.60
Purchase #6	$145.54	13.686%	$165.4586	$165.46	$165.45	$165.50
Purchase #7	$169.82	10.784%	$188.1334	$188.13	$188.15	$188.10
7 purchase totals =	$778.98		$863.8012	$863.80	$863.80	$863.70