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	$55.41	11.156%	$61.5915	$61.59	$61.60	$61.60
Purchase #2	$155.54	3.553%	$161.0663	$161.07	$161.05	$161.10
Purchase #3	$160.35	9.559%	$175.6779	$175.68	$175.70	$175.70
Purchase #4	$94.26	6.484%	$100.3718	$100.37	$100.35	$100.40
Purchase #5	$242.71	5.285%	$255.5372	$255.54	$255.55	$255.50
Purchase #6	$50.83	6.383%	$54.0745	$54.07	$54.05	$54.10
Purchase #7	$214.35	11.469%	$238.9338	$238.93	$238.95	$238.90
7 purchase totals =	$973.45		$1,047.2530	$1,047.25	$1,047.25	$1,047.30