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	$102.71	13.839%	$116.924	$116.92	$116.90	$116.90
Purchase #2	$22.30	5.482%	$23.5225	$23.52	$23.50	$23.50
Purchase #3	$232.27	4.218%	$242.0671	$242.07	$242.05	$242.10
Purchase #4	$40.81	3.262%	$42.1412	$42.14	$42.15	$42.10
Purchase #5	$177.51	5.445%	$187.1754	$187.18	$187.20	$187.20
Purchase #6	$164.91	4.334%	$172.0572	$172.06	$172.05	$172.10
Purchase #7	$160.28	11.641%	$178.9382	$178.94	$178.95	$178.90
7 purchase totals =	$900.79		$962.8256	$962.83	$962.80	$962.80