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	$77.56	12.831%	$87.5117	$87.51	$87.50	$87.50
Purchase #2	$160.41	4.519%	$167.6589	$167.66	$167.65	$167.70
Purchase #3	$43.43	4.545%	$45.4039	$45.40	$45.40	$45.40
Purchase #4	$194.64	7.727%	$209.6798	$209.68	$209.70	$209.70
Purchase #5	$240.72	12.410%	$270.5934	$270.59	$270.60	$270.60
Purchase #6	$21.26	3.218%	$21.9441	$21.94	$21.95	$21.90
Purchase #7	$235.64	9.856%	$258.8647	$258.86	$258.85	$258.90
7 purchase totals =	$973.66		$1,061.6565	$1,061.64	$1,061.65	$1,061.70