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	$38.91	12.205%	$43.659	$43.66	$43.65	$43.70
Purchase #2	$158.59	3.725%	$164.4975	$164.50	$164.50	$164.50
Purchase #3	$105.27	7.569%	$113.2379	$113.24	$113.25	$113.20
Purchase #4	$141.94	9.823%	$155.8828	$155.88	$155.90	$155.90
Purchase #5	$172.43	11.650%	$192.5181	$192.52	$192.50	$192.50
Purchase #6	$190.42	8.614%	$206.8228	$206.82	$206.80	$206.80
Purchase #7	$242.35	10.605%	$268.0512	$268.05	$268.05	$268.10
7 purchase totals =	$1,049.91		$1,144.6693	$1,144.67	$1,144.65	$1,144.70