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	$58.26	11.655%	$65.0502	$65.05	$65.05	$65.10
Purchase #2	$145.50	13.541%	$165.2022	$165.20	$165.20	$165.20
Purchase #3	$112.89	12.731%	$127.262	$127.26	$127.25	$127.30
Purchase #4	$15.72	12.807%	$17.7333	$17.73	$17.75	$17.70
Purchase #5	$213.52	10.434%	$235.7987	$235.80	$235.80	$235.80
Purchase #6	$200.48	13.613%	$227.7713	$227.77	$227.75	$227.80
Purchase #7	$158.53	4.376%	$165.4673	$165.47	$165.45	$165.50
7 purchase totals =	$904.90		$1,004.2850	$1,004.28	$1,004.25	$1,004.40