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	$110.85	3.659%	$114.906	$114.91	$114.90	$114.90
Purchase #2	$23.52	10.137%	$25.9042	$25.90	$25.90	$25.90
Purchase #3	$112.31	12.218%	$126.032	$126.03	$126.05	$126.00
Purchase #4	$127.67	7.264%	$136.9439	$136.94	$136.95	$136.90
Purchase #5	$172.89	13.538%	$196.2958	$196.30	$196.30	$196.30
Purchase #6	$239.69	11.664%	$267.6474	$267.65	$267.65	$267.60
Purchase #7	$7.26	6.491%	$7.7312	$7.73	$7.75	$7.70
7 purchase totals =	$794.19		$875.4605	$875.46	$875.50	$875.30