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	$103.58	4.361%	$108.0971	$108.10	$108.10	$108.10
Purchase #2	$13.98	5.183%	$14.7046	$14.70	$14.70	$14.70
Purchase #3	$82.55	9.449%	$90.3501	$90.35	$90.35	$90.40
Purchase #4	$54.43	12.812%	$61.4036	$61.40	$61.40	$61.40
Purchase #5	$44.62	12.617%	$50.2497	$50.25	$50.25	$50.20
Purchase #6	$94.89	5.496%	$100.1052	$100.11	$100.10	$100.10
Purchase #7	$166.95	6.374%	$177.5914	$177.59	$177.60	$177.60
7 purchase totals =	$561.00		$602.5017	$602.50	$602.50	$602.50