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	$59.83	9.664%	$65.612	$65.61	$65.60	$65.60
Purchase #2	$94.27	5.392%	$99.353	$99.35	$99.35	$99.40
Purchase #3	$20.29	3.570%	$21.0144	$21.01	$21.00	$21.00
Purchase #4	$244.51	5.551%	$258.0828	$258.08	$258.10	$258.10
Purchase #5	$35.49	6.227%	$37.7	$37.70	$37.70	$37.70
Purchase #6	$33.79	11.560%	$37.6961	$37.70	$37.70	$37.70
Purchase #7	$186.48	11.790%	$208.466	$208.47	$208.45	$208.50
7 purchase totals =	$674.66		$727.9243	$727.92	$727.90	$728.00