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	$174.46	11.777%	$195.0062	$195.01	$195.00	$195.00
Purchase #2	$69.54	12.849%	$78.4752	$78.48	$78.50	$78.50
Purchase #3	$116.39	3.314%	$120.2472	$120.25	$120.25	$120.20
Purchase #4	$136.80	7.296%	$146.7809	$146.78	$146.80	$146.80
Purchase #5	$29.38	12.624%	$33.0889	$33.09	$33.10	$33.10
Purchase #6	$32.47	13.782%	$36.945	$36.95	$36.95	$36.90
Purchase #7	$160.87	7.149%	$172.3706	$172.37	$172.35	$172.40
7 purchase totals =	$719.91		$782.9140	$782.93	$782.95	$782.90