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	$58.52	5.458%	$61.714	$61.71	$61.70	$61.70
Purchase #2	$35.71	12.195%	$40.0648	$40.06	$40.05	$40.10
Purchase #3	$46.42	11.809%	$51.9017	$51.90	$51.90	$51.90
Purchase #4	$11.54	13.513%	$13.0994	$13.10	$13.10	$13.10
Purchase #5	$32.64	13.348%	$36.9968	$37.00	$37.00	$37.00
Purchase #6	$233.60	9.432%	$255.6332	$255.63	$255.65	$255.60
Purchase #7	$102.96	11.402%	$114.6995	$114.70	$114.70	$114.70
7 purchase totals =	$521.39		$574.1094	$574.10	$574.10	$574.10