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	$190.63	3.105%	$196.5491	$196.55	$196.55	$196.50
Purchase #2	$56.78	5.357%	$59.8217	$59.82	$59.80	$59.80
Purchase #3	$87.72	9.383%	$95.9508	$95.95	$95.95	$96.00
Purchase #4	$39.39	7.600%	$42.3836	$42.38	$42.40	$42.40
Purchase #5	$48.79	6.651%	$52.035	$52.04	$52.05	$52.00
Purchase #6	$92.46	12.563%	$104.0757	$104.08	$104.10	$104.10
Purchase #7	$231.69	10.501%	$256.0198	$256.02	$256.00	$256.00
7 purchase totals =	$747.46		$806.8357	$806.84	$806.85	$806.80