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	$43.81	7.137%	$46.9367	$46.94	$46.95	$46.90
Purchase #2	$124.65	11.520%	$139.0097	$139.01	$139.00	$139.00
Purchase #3	$158.54	5.498%	$167.2565	$167.26	$167.25	$167.30
Purchase #4	$118.69	12.162%	$133.1251	$133.13	$133.15	$133.10
Purchase #5	$100.94	10.720%	$111.7608	$111.76	$111.75	$111.80
Purchase #6	$240.75	6.362%	$256.0665	$256.07	$256.05	$256.10
Purchase #7	$96.98	3.102%	$99.9883	$99.99	$100.00	$100.00
7 purchase totals =	$884.36		$954.1436	$954.16	$954.15	$954.20