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	$76.29	7.531%	$82.0354	$82.04	$82.05	$82.00
Purchase #2	$25.45	9.598%	$27.8927	$27.89	$27.90	$27.90
Purchase #3	$21.74	6.833%	$23.2255	$23.23	$23.25	$23.20
Purchase #4	$62.45	12.206%	$70.0726	$70.07	$70.05	$70.10
Purchase #5	$44.55	4.256%	$46.446	$46.45	$46.45	$46.40
Purchase #6	$69.48	4.561%	$72.649	$72.65	$72.65	$72.60
Purchase #7	$33.55	6.242%	$35.6442	$35.64	$35.65	$35.60
7 purchase totals =	$333.51		$357.9654	$357.97	$358.00	$357.80