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	$221.90	9.105%	$242.104	$242.10	$242.10	$242.10
Purchase #2	$69.83	5.359%	$73.5722	$73.57	$73.55	$73.60
Purchase #3	$42.66	7.560%	$45.8851	$45.89	$45.90	$45.90
Purchase #4	$196.80	4.211%	$205.0872	$205.09	$205.10	$205.10
Purchase #5	$29.57	11.462%	$32.9593	$32.96	$32.95	$33.00
Purchase #6	$209.78	13.251%	$237.5779	$237.58	$237.60	$237.60
Purchase #7	$224.91	10.432%	$248.3726	$248.37	$248.35	$248.40
7 purchase totals =	$995.45		$1,085.5583	$1,085.56	$1,085.55	$1,085.70