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	$92.63	10.128%	$102.0116	$102.01	$102.00	$102.00
Purchase #2	$118.25	10.837%	$131.0648	$131.06	$131.05	$131.10
Purchase #3	$129.50	10.201%	$142.7103	$142.71	$142.70	$142.70
Purchase #4	$158.36	8.619%	$172.009	$172.01	$172.00	$172.00
Purchase #5	$222.81	13.297%	$252.437	$252.44	$252.45	$252.40
Purchase #6	$96.87	6.597%	$103.2605	$103.26	$103.25	$103.30
Purchase #7	$194.93	6.613%	$207.8207	$207.82	$207.80	$207.80
7 purchase totals =	$1,013.35		$1,111.3139	$1,111.31	$1,111.25	$1,111.30