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	$119.28	3.605%	$123.58	$123.58	$123.60	$123.60
Purchase #2	$101.63	6.464%	$108.1994	$108.20	$108.20	$108.20
Purchase #3	$176.92	11.177%	$196.6943	$196.69	$196.70	$196.70
Purchase #4	$132.37	6.595%	$141.0998	$141.10	$141.10	$141.10
Purchase #5	$55.62	11.429%	$61.9768	$61.98	$62.00	$62.00
Purchase #6	$127.98	13.691%	$145.5017	$145.50	$145.50	$145.50
Purchase #7	$227.38	6.274%	$241.6458	$241.65	$241.65	$241.60
7 purchase totals =	$941.18		$1,018.6978	$1,018.70	$1,018.75	$1,018.70