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	$130.86	11.112%	$145.4012	$145.40	$145.40	$145.40
Purchase #2	$20.73	5.461%	$21.8621	$21.86	$21.85	$21.90
Purchase #3	$48.95	4.380%	$51.094	$51.09	$51.10	$51.10
Purchase #4	$161.43	11.873%	$180.5966	$180.60	$180.60	$180.60
Purchase #5	$80.62	11.452%	$89.8526	$89.85	$89.85	$89.90
Purchase #6	$155.99	8.527%	$169.2913	$169.29	$169.30	$169.30
Purchase #7	$34.30	4.453%	$35.8274	$35.83	$35.85	$35.80
7 purchase totals =	$632.88		$693.9252	$693.92	$693.95	$694.00