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	$208.80	11.473%	$232.7556	$232.76	$232.75	$232.80
Purchase #2	$155.59	8.537%	$168.8727	$168.87	$168.85	$168.90
Purchase #3	$239.50	9.767%	$262.892	$262.89	$262.90	$262.90
Purchase #4	$106.83	4.504%	$111.6416	$111.64	$111.65	$111.60
Purchase #5	$109.59	6.816%	$117.0597	$117.06	$117.05	$117.10
Purchase #6	$49.45	8.175%	$53.4925	$53.49	$53.50	$53.50
Purchase #7	$98.81	3.677%	$102.4432	$102.44	$102.45	$102.40
7 purchase totals =	$968.57		$1,049.1573	$1,049.15	$1,049.15	$1,049.20