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	$109.33	4.499%	$114.2488	$114.25	$114.25	$114.20
Purchase #2	$212.33	4.792%	$222.5049	$222.50	$222.50	$222.50
Purchase #3	$32.91	5.163%	$34.6091	$34.61	$34.60	$34.60
Purchase #4	$99.63	13.111%	$112.6925	$112.69	$112.70	$112.70
Purchase #5	$188.77	13.595%	$214.4333	$214.43	$214.45	$214.40
Purchase #6	$32.89	9.715%	$36.0853	$36.09	$36.10	$36.10
Purchase #7	$114.40	10.264%	$126.142	$126.14	$126.15	$126.10
7 purchase totals =	$790.26		$860.7159	$860.71	$860.75	$860.60