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	$215.71	9.853%	$236.9639	$236.96	$236.95	$237.00
Purchase #2	$247.35	6.560%	$263.5762	$263.58	$263.60	$263.60
Purchase #3	$105.45	5.699%	$111.4596	$111.46	$111.45	$111.50
Purchase #4	$26.95	7.802%	$29.0526	$29.05	$29.05	$29.10
Purchase #5	$112.35	10.268%	$123.8861	$123.89	$123.90	$123.90
Purchase #6	$116.37	8.794%	$126.6036	$126.60	$126.60	$126.60
Purchase #7	$46.30	9.604%	$50.7467	$50.75	$50.75	$50.70
7 purchase totals =	$870.48		$942.2887	$942.29	$942.30	$942.40