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	$165.53	4.836%	$173.535	$173.54	$173.55	$173.50
Purchase #2	$10.42	11.361%	$11.6038	$11.60	$11.60	$11.60
Purchase #3	$178.49	10.840%	$197.8383	$197.84	$197.85	$197.80
Purchase #4	$34.52	8.716%	$37.5288	$37.53	$37.55	$37.50
Purchase #5	$133.63	6.334%	$142.0941	$142.09	$142.10	$142.10
Purchase #6	$124.61	10.766%	$138.0255	$138.03	$138.05	$138.00
Purchase #7	$53.59	11.528%	$59.7679	$59.77	$59.75	$59.80
7 purchase totals =	$700.79		$760.3934	$760.40	$760.45	$760.30