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	$118.36	8.291%	$128.1732	$128.17	$128.15	$128.20
Purchase #2	$188.85	4.351%	$197.0669	$197.07	$197.05	$197.10
Purchase #3	$173.46	8.287%	$187.8346	$187.83	$187.85	$187.80
Purchase #4	$105.38	4.447%	$110.0662	$110.07	$110.05	$110.10
Purchase #5	$135.51	5.402%	$142.8303	$142.83	$142.85	$142.80
Purchase #6	$247.32	3.836%	$256.8072	$256.81	$256.80	$256.80
Purchase #7	$118.39	4.638%	$123.8809	$123.88	$123.90	$123.90
7 purchase totals =	$1,087.27		$1,146.6593	$1,146.66	$1,146.65	$1,146.70