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	$127.61	13.198%	$144.452	$144.45	$144.45	$144.50
Purchase #2	$52.52	13.500%	$59.6102	$59.61	$59.60	$59.60
Purchase #3	$13.90	4.643%	$14.5454	$14.55	$14.55	$14.50
Purchase #4	$13.41	4.279%	$13.9838	$13.98	$14.00	$14.00
Purchase #5	$212.75	7.456%	$228.6126	$228.61	$228.60	$228.60
Purchase #6	$221.73	4.382%	$231.4462	$231.45	$231.45	$231.40
Purchase #7	$220.36	9.304%	$240.8623	$240.86	$240.85	$240.90
7 purchase totals =	$862.28		$933.5125	$933.51	$933.50	$933.50