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	$10.53	8.781%	$11.4546	$11.45	$11.45	$11.50
Purchase #2	$77.38	4.412%	$80.794	$80.79	$80.80	$80.80
Purchase #3	$151.68	12.411%	$170.505	$170.51	$170.50	$170.50
Purchase #4	$191.42	10.710%	$211.9211	$211.92	$211.90	$211.90
Purchase #5	$67.64	7.752%	$72.8835	$72.88	$72.90	$72.90
Purchase #6	$47.90	12.167%	$53.728	$53.73	$53.75	$53.70
Purchase #7	$146.81	5.189%	$154.428	$154.43	$154.45	$154.40
7 purchase totals =	$693.36		$755.7142	$755.71	$755.75	$755.70