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	$46.25	3.686%	$47.9548	$47.95	$47.95	$48.00
Purchase #2	$127.91	3.611%	$132.5288	$132.53	$132.55	$132.50
Purchase #3	$112.56	5.318%	$118.5459	$118.55	$118.55	$118.50
Purchase #4	$95.42	4.574%	$99.7845	$99.78	$99.80	$99.80
Purchase #5	$208.86	6.108%	$221.6172	$221.62	$221.60	$221.60
Purchase #6	$178.92	12.290%	$200.9093	$200.91	$200.90	$200.90
Purchase #7	$168.39	3.607%	$174.4638	$174.46	$174.45	$174.50
7 purchase totals =	$938.31		$995.8043	$995.80	$995.80	$995.80