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	$206.54	3.854%	$214.5001	$214.50	$214.50	$214.50
Purchase #2	$29.86	5.814%	$31.5961	$31.60	$31.60	$31.60
Purchase #3	$149.34	5.612%	$157.721	$157.72	$157.70	$157.70
Purchase #4	$30.72	8.696%	$33.3914	$33.39	$33.40	$33.40
Purchase #5	$29.78	9.441%	$32.5915	$32.59	$32.60	$32.60
Purchase #6	$94.86	12.729%	$106.9347	$106.93	$106.95	$106.90
Purchase #7	$176.44	11.108%	$196.039	$196.04	$196.05	$196.00
7 purchase totals =	$717.54		$772.7738	$772.77	$772.80	$772.70