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	$197.46	5.678%	$208.6718	$208.67	$208.65	$208.70
Purchase #2	$190.71	3.306%	$197.0149	$197.01	$197.00	$197.00
Purchase #3	$160.69	5.104%	$168.8916	$168.89	$168.90	$168.90
Purchase #4	$130.33	7.595%	$140.2286	$140.23	$140.25	$140.20
Purchase #5	$99.51	6.272%	$105.7513	$105.75	$105.75	$105.80
Purchase #6	$189.83	11.200%	$211.091	$211.09	$211.10	$211.10
Purchase #7	$241.47	6.131%	$256.2745	$256.27	$256.25	$256.30
7 purchase totals =	$1,210.00		$1,287.9237	$1,287.91	$1,287.90	$1,288.00