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	$54.78	13.620%	$62.241	$62.24	$62.25	$62.20
Purchase #2	$38.81	5.145%	$40.8068	$40.81	$40.80	$40.80
Purchase #3	$198.46	11.803%	$221.8842	$221.88	$221.90	$221.90
Purchase #4	$247.35	6.128%	$262.5076	$262.51	$262.50	$262.50
Purchase #5	$207.81	12.484%	$233.753	$233.75	$233.75	$233.80
Purchase #6	$151.65	10.569%	$167.6779	$167.68	$167.70	$167.70
Purchase #7	$42.99	3.780%	$44.615	$44.62	$44.60	$44.60
7 purchase totals =	$941.85		$1,033.4855	$1,033.49	$1,033.50	$1,033.50