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	$112.51	13.632%	$127.8474	$127.85	$127.85	$127.80
Purchase #2	$76.27	5.328%	$80.3337	$80.33	$80.35	$80.30
Purchase #3	$95.42	5.809%	$100.9629	$100.96	$100.95	$101.00
Purchase #4	$61.63	3.334%	$63.6847	$63.68	$63.70	$63.70
Purchase #5	$235.47	8.730%	$256.0265	$256.03	$256.05	$256.00
Purchase #6	$140.94	12.392%	$158.4053	$158.41	$158.40	$158.40
Purchase #7	$155.43	5.849%	$164.5211	$164.52	$164.50	$164.50
7 purchase totals =	$877.67		$951.7816	$951.78	$951.80	$951.70