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	$106.59	4.374%	$111.2522	$111.25	$111.25	$111.30
Purchase #2	$107.38	4.338%	$112.0381	$112.04	$112.05	$112.00
Purchase #3	$225.94	5.228%	$237.7521	$237.75	$237.75	$237.80
Purchase #4	$95.82	13.349%	$108.611	$108.61	$108.60	$108.60
Purchase #5	$154.83	11.380%	$172.4497	$172.45	$172.45	$172.40
Purchase #6	$69.25	6.656%	$73.8593	$73.86	$73.85	$73.90
Purchase #7	$223.88	8.304%	$242.471	$242.47	$242.45	$242.50
7 purchase totals =	$983.69		$1,058.4334	$1,058.43	$1,058.40	$1,058.50