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	$238.70	10.846%	$264.5894	$264.59	$264.60	$264.60
Purchase #2	$64.70	13.102%	$73.177	$73.18	$73.20	$73.20
Purchase #3	$169.82	12.211%	$190.5567	$190.56	$190.55	$190.60
Purchase #4	$137.95	5.204%	$145.1289	$145.13	$145.15	$145.10
Purchase #5	$106.81	5.529%	$112.7155	$112.72	$112.70	$112.70
Purchase #6	$126.87	4.479%	$132.5525	$132.55	$132.55	$132.60
Purchase #7	$143.50	3.438%	$148.4335	$148.43	$148.45	$148.40
7 purchase totals =	$988.35		$1,067.1535	$1,067.16	$1,067.20	$1,067.20