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	$200.82	3.779%	$208.409	$208.41	$208.40	$208.40
Purchase #2	$116.56	13.617%	$132.432	$132.43	$132.45	$132.40
Purchase #3	$11.45	11.340%	$12.7484	$12.75	$12.75	$12.70
Purchase #4	$182.47	6.598%	$194.5094	$194.51	$194.50	$194.50
Purchase #5	$231.59	13.735%	$263.3989	$263.40	$263.40	$263.40
Purchase #6	$127.92	13.651%	$145.3824	$145.38	$145.40	$145.40
Purchase #7	$39.68	6.164%	$42.1259	$42.13	$42.15	$42.10
7 purchase totals =	$910.49		$999.0060	$999.01	$999.05	$998.90