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	$119.72	5.242%	$125.9957	$126.00	$126.00	$126.00
Purchase #2	$162.87	9.814%	$178.8541	$178.85	$178.85	$178.90
Purchase #3	$246.75	9.583%	$270.3961	$270.40	$270.40	$270.40
Purchase #4	$100.48	11.434%	$111.9689	$111.97	$111.95	$112.00
Purchase #5	$160.62	4.333%	$167.5797	$167.58	$167.60	$167.60
Purchase #6	$155.67	7.580%	$167.4698	$167.47	$167.45	$167.50
Purchase #7	$98.40	10.810%	$109.037	$109.04	$109.05	$109.00
7 purchase totals =	$1,044.51		$1,131.3013	$1,131.31	$1,131.30	$1,131.40