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	$111.48	6.833%	$119.0974	$119.10	$119.10	$119.10
Purchase #2	$109.37	6.498%	$116.4769	$116.48	$116.50	$116.50
Purchase #3	$215.26	4.627%	$225.2201	$225.22	$225.20	$225.20
Purchase #4	$10.60	4.354%	$11.0615	$11.06	$11.05	$11.10
Purchase #5	$236.77	10.396%	$261.3846	$261.38	$261.40	$261.40
Purchase #6	$116.63	8.307%	$126.3185	$126.32	$126.30	$126.30
Purchase #7	$141.83	11.440%	$158.0554	$158.06	$158.05	$158.10
7 purchase totals =	$941.94		$1,017.6144	$1,017.62	$1,017.60	$1,017.70