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	$54.54	9.207%	$59.5615	$59.56	$59.55	$59.60
Purchase #2	$248.74	4.866%	$260.8437	$260.84	$260.85	$260.80
Purchase #3	$55.92	13.743%	$63.6051	$63.61	$63.60	$63.60
Purchase #4	$221.75	6.435%	$236.0196	$236.02	$236.00	$236.00
Purchase #5	$57.45	7.828%	$61.9472	$61.95	$61.95	$61.90
Purchase #6	$55.87	10.188%	$61.562	$61.56	$61.55	$61.60
Purchase #7	$38.43	13.154%	$43.4851	$43.49	$43.50	$43.50
7 purchase totals =	$732.70		$787.0242	$787.03	$787.00	$787.00