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	$143.56	7.147%	$153.8202	$153.82	$153.80	$153.80
Purchase #2	$125.99	11.153%	$140.0417	$140.04	$140.05	$140.00
Purchase #3	$166.43	10.265%	$183.514	$183.51	$183.50	$183.50
Purchase #4	$179.32	4.550%	$187.4791	$187.48	$187.50	$187.50
Purchase #5	$141.27	12.491%	$158.916	$158.92	$158.90	$158.90
Purchase #6	$151.34	10.431%	$167.1263	$167.13	$167.15	$167.10
Purchase #7	$135.52	7.286%	$145.394	$145.39	$145.40	$145.40
7 purchase totals =	$1,043.43		$1,136.2913	$1,136.29	$1,136.30	$1,136.20