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	$130.30	11.609%	$145.4265	$145.43	$145.45	$145.40
Purchase #2	$15.60	11.143%	$17.3383	$17.34	$17.35	$17.30
Purchase #3	$58.89	3.761%	$61.1049	$61.10	$61.10	$61.10
Purchase #4	$116.43	7.139%	$124.7419	$124.74	$124.75	$124.70
Purchase #5	$215.56	3.664%	$223.4581	$223.46	$223.45	$223.50
Purchase #6	$155.64	3.393%	$160.9209	$160.92	$160.90	$160.90
Purchase #7	$139.65	8.438%	$151.4337	$151.43	$151.45	$151.40
7 purchase totals =	$832.07		$884.4243	$884.42	$884.45	$884.30