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	$218.38	5.702%	$230.832	$230.83	$230.85	$230.80
Purchase #2	$42.43	12.131%	$47.5772	$47.58	$47.60	$47.60
Purchase #3	$73.87	3.530%	$76.4776	$76.48	$76.50	$76.50
Purchase #4	$126.65	3.675%	$131.3044	$131.30	$131.30	$131.30
Purchase #5	$163.59	13.605%	$185.8464	$185.85	$185.85	$185.80
Purchase #6	$244.72	12.212%	$274.6052	$274.61	$274.60	$274.60
Purchase #7	$184.80	8.462%	$200.4378	$200.44	$200.45	$200.40
7 purchase totals =	$1,054.44		$1,147.0806	$1,147.09	$1,147.15	$1,147.00