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	$119.87	11.726%	$133.926	$133.93	$133.95	$133.90
Purchase #2	$69.98	10.263%	$77.162	$77.16	$77.15	$77.20
Purchase #3	$113.27	6.414%	$120.5351	$120.54	$120.55	$120.50
Purchase #4	$52.69	13.291%	$59.693	$59.69	$59.70	$59.70
Purchase #5	$52.32	7.176%	$56.0745	$56.07	$56.05	$56.10
Purchase #6	$143.83	6.615%	$153.3444	$153.34	$153.35	$153.30
Purchase #7	$170.43	12.752%	$192.1632	$192.16	$192.15	$192.20
7 purchase totals =	$722.39		$792.8982	$792.89	$792.90	$792.90