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	$158.58	3.704%	$164.4538	$164.45	$164.45	$164.50
Purchase #2	$83.89	13.226%	$94.9853	$94.99	$95.00	$95.00
Purchase #3	$147.34	6.408%	$156.7815	$156.78	$156.80	$156.80
Purchase #4	$205.40	3.831%	$213.2689	$213.27	$213.25	$213.30
Purchase #5	$187.62	11.103%	$208.4514	$208.45	$208.45	$208.50
Purchase #6	$121.61	5.395%	$128.1709	$128.17	$128.15	$128.20
Purchase #7	$124.39	12.373%	$139.7808	$139.78	$139.80	$139.80
7 purchase totals =	$1,028.83		$1,105.8926	$1,105.89	$1,105.90	$1,106.10