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	$184.64	4.493%	$192.9359	$192.94	$192.95	$192.90
Purchase #2	$167.60	4.569%	$175.2576	$175.26	$175.25	$175.30
Purchase #3	$12.94	7.423%	$13.9005	$13.90	$13.90	$13.90
Purchase #4	$211.82	8.412%	$229.6383	$229.64	$229.65	$229.60
Purchase #5	$27.68	13.583%	$31.4398	$31.44	$31.45	$31.40
Purchase #6	$102.77	8.873%	$111.8888	$111.89	$111.90	$111.90
Purchase #7	$48.97	3.330%	$50.6007	$50.60	$50.60	$50.60
7 purchase totals =	$756.42		$805.6616	$805.67	$805.70	$805.60