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	$237.64	10.442%	$262.4544	$262.45	$262.45	$262.50
Purchase #2	$47.85	7.256%	$51.322	$51.32	$51.30	$51.30
Purchase #3	$60.35	4.685%	$63.1774	$63.18	$63.20	$63.20
Purchase #4	$155.32	12.779%	$175.1683	$175.17	$175.15	$175.20
Purchase #5	$127.80	12.107%	$143.2727	$143.27	$143.25	$143.30
Purchase #6	$115.45	10.472%	$127.5399	$127.54	$127.55	$127.50
Purchase #7	$150.29	5.512%	$158.574	$158.57	$158.55	$158.60
7 purchase totals =	$894.70		$981.5087	$981.50	$981.45	$981.60