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	$192.98	11.418%	$215.0145	$215.01	$215.00	$215.00
Purchase #2	$34.57	5.503%	$36.4724	$36.47	$36.45	$36.50
Purchase #3	$38.38	10.866%	$42.5504	$42.55	$42.55	$42.60
Purchase #4	$8.78	7.655%	$9.4521	$9.45	$9.45	$9.50
Purchase #5	$54.77	9.422%	$59.9304	$59.93	$59.95	$59.90
Purchase #6	$116.63	4.510%	$121.89	$121.89	$121.90	$121.90
Purchase #7	$202.62	3.358%	$209.424	$209.42	$209.40	$209.40
7 purchase totals =	$648.73		$694.7338	$694.72	$694.70	$694.80