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	$85.62	11.656%	$95.5999	$95.60	$95.60	$95.60
Purchase #2	$220.87	6.203%	$234.5706	$234.57	$234.55	$234.60
Purchase #3	$47.25	11.319%	$52.5982	$52.60	$52.60	$52.60
Purchase #4	$165.45	13.338%	$187.5177	$187.52	$187.50	$187.50
Purchase #5	$54.45	4.677%	$56.9966	$57.00	$57.00	$57.00
Purchase #6	$86.65	3.763%	$89.9106	$89.91	$89.90	$89.90
Purchase #7	$41.61	8.703%	$45.2313	$45.23	$45.25	$45.20
7 purchase totals =	$701.90		$762.4249	$762.43	$762.40	$762.40