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	$161.54	5.156%	$169.869	$169.87	$169.85	$169.90
Purchase #2	$95.94	10.497%	$106.0108	$106.01	$106.00	$106.00
Purchase #3	$99.50	11.769%	$111.2102	$111.21	$111.20	$111.20
Purchase #4	$59.64	11.746%	$66.6453	$66.65	$66.65	$66.60
Purchase #5	$33.42	11.326%	$37.2051	$37.21	$37.20	$37.20
Purchase #6	$154.41	8.726%	$167.8838	$167.88	$167.90	$167.90
Purchase #7	$53.52	7.722%	$57.6528	$57.65	$57.65	$57.70
7 purchase totals =	$657.97		$716.4770	$716.48	$716.45	$716.50