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	$98.52	13.649%	$111.967	$111.97	$111.95	$112.00
Purchase #2	$69.26	4.349%	$72.2721	$72.27	$72.25	$72.30
Purchase #3	$29.66	4.768%	$31.0742	$31.07	$31.05	$31.10
Purchase #4	$230.31	13.279%	$260.8929	$260.89	$260.90	$260.90
Purchase #5	$68.47	11.440%	$76.303	$76.30	$76.30	$76.30
Purchase #6	$55.89	10.735%	$61.8898	$61.89	$61.90	$61.90
Purchase #7	$200.67	3.820%	$208.3356	$208.34	$208.35	$208.30
7 purchase totals =	$752.78		$822.7346	$822.73	$822.70	$822.80