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	$246.61	6.577%	$262.8295	$262.83	$262.85	$262.80
Purchase #2	$40.58	6.624%	$43.268	$43.27	$43.25	$43.30
Purchase #3	$10.92	6.125%	$11.5889	$11.59	$11.60	$11.60
Purchase #4	$202.67	3.211%	$209.1777	$209.18	$209.20	$209.20
Purchase #5	$171.60	11.201%	$190.8209	$190.82	$190.80	$190.80
Purchase #6	$197.48	3.640%	$204.6683	$204.67	$204.65	$204.70
Purchase #7	$107.89	3.488%	$111.6532	$111.65	$111.65	$111.70
7 purchase totals =	$977.75		$1,034.0065	$1,034.01	$1,034.00	$1,034.10