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	$149.60	11.659%	$167.0419	$167.04	$167.05	$167.00
Purchase #2	$92.58	8.664%	$100.6011	$100.60	$100.60	$100.60
Purchase #3	$50.83	9.540%	$55.6792	$55.68	$55.70	$55.70
Purchase #4	$224.86	5.305%	$236.7888	$236.79	$236.80	$236.80
Purchase #5	$223.42	6.383%	$237.6809	$237.68	$237.70	$237.70
Purchase #6	$226.50	9.679%	$248.4229	$248.42	$248.40	$248.40
Purchase #7	$54.90	8.587%	$59.6143	$59.61	$59.60	$59.60
7 purchase totals =	$1,022.69		$1,105.8291	$1,105.82	$1,105.85	$1,105.80