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	$59.57	10.345%	$65.7325	$65.73	$65.75	$65.70
Purchase #2	$63.78	3.383%	$65.9377	$65.94	$65.95	$65.90
Purchase #3	$175.63	3.679%	$182.0914	$182.09	$182.10	$182.10
Purchase #4	$166.59	11.512%	$185.7678	$185.77	$185.75	$185.80
Purchase #5	$67.49	5.411%	$71.1419	$71.14	$71.15	$71.10
Purchase #6	$20.42	12.781%	$23.0299	$23.03	$23.05	$23.00
Purchase #7	$111.56	8.207%	$120.7157	$120.72	$120.70	$120.70
7 purchase totals =	$665.04		$714.4169	$714.42	$714.45	$714.30