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	$244.87	9.871%	$269.0411	$269.04	$269.05	$269.00
Purchase #2	$135.94	5.563%	$143.5023	$143.50	$143.50	$143.50
Purchase #3	$223.59	3.806%	$232.0998	$232.10	$232.10	$232.10
Purchase #4	$83.76	6.376%	$89.1005	$89.10	$89.10	$89.10
Purchase #5	$222.86	3.624%	$230.9364	$230.94	$230.95	$230.90
Purchase #6	$106.79	7.585%	$114.89	$114.89	$114.90	$114.90
Purchase #7	$135.88	8.509%	$147.442	$147.44	$147.45	$147.40
7 purchase totals =	$1,153.69		$1,227.0121	$1,227.01	$1,227.05	$1,226.90