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	$219.96	6.769%	$234.8491	$234.85	$234.85	$234.80
Purchase #2	$10.39	13.350%	$11.7771	$11.78	$11.80	$11.80
Purchase #3	$19.52	10.779%	$21.6241	$21.62	$21.60	$21.60
Purchase #4	$83.46	7.192%	$89.4624	$89.46	$89.45	$89.50
Purchase #5	$114.68	4.294%	$119.6044	$119.60	$119.60	$119.60
Purchase #6	$145.63	8.835%	$158.4964	$158.50	$158.50	$158.50
Purchase #7	$208.51	10.126%	$229.6237	$229.62	$229.60	$229.60
7 purchase totals =	$802.15		$865.4372	$865.43	$865.40	$865.40