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	$146.98	3.808%	$152.577	$152.58	$152.60	$152.60
Purchase #2	$146.76	3.572%	$152.0023	$152.00	$152.00	$152.00
Purchase #3	$11.89	9.423%	$13.0104	$13.01	$13.00	$13.00
Purchase #4	$135.54	6.220%	$143.9706	$143.97	$143.95	$144.00
Purchase #5	$137.64	3.751%	$142.8029	$142.80	$142.80	$142.80
Purchase #6	$61.78	6.604%	$65.86	$65.86	$65.85	$65.90
Purchase #7	$38.39	4.422%	$40.0876	$40.09	$40.10	$40.10
7 purchase totals =	$678.98		$710.3108	$710.31	$710.30	$710.40