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	$68.45	4.580%	$71.585	$71.59	$71.60	$71.60
Purchase #2	$182.51	9.837%	$200.4635	$200.46	$200.45	$200.50
Purchase #3	$131.35	7.664%	$141.4167	$141.42	$141.40	$141.40
Purchase #4	$108.95	8.347%	$118.0441	$118.04	$118.05	$118.00
Purchase #5	$53.65	6.461%	$57.1163	$57.12	$57.10	$57.10
Purchase #6	$231.82	4.287%	$241.7581	$241.76	$241.75	$241.80
Purchase #7	$35.99	4.580%	$37.6383	$37.64	$37.65	$37.60
7 purchase totals =	$812.72		$868.0220	$868.03	$868.00	$868.00