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	$193.93	3.371%	$200.4674	$200.47	$200.45	$200.50
Purchase #2	$41.82	9.330%	$45.7218	$45.72	$45.70	$45.70
Purchase #3	$196.43	10.653%	$217.3557	$217.36	$217.35	$217.40
Purchase #4	$153.31	6.135%	$162.7156	$162.72	$162.70	$162.70
Purchase #5	$158.47	3.182%	$163.5125	$163.51	$163.50	$163.50
Purchase #6	$177.31	5.522%	$187.1011	$187.10	$187.10	$187.10
Purchase #7	$115.86	3.137%	$119.4945	$119.49	$119.50	$119.50
7 purchase totals =	$1,037.13		$1,096.3686	$1,096.37	$1,096.30	$1,096.40