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	$184.94	13.365%	$209.6572	$209.66	$209.65	$209.70
Purchase #2	$22.35	13.589%	$25.3871	$25.39	$25.40	$25.40
Purchase #3	$187.83	5.172%	$197.5446	$197.54	$197.55	$197.50
Purchase #4	$103.63	9.200%	$113.164	$113.16	$113.15	$113.20
Purchase #5	$103.89	9.136%	$113.3814	$113.38	$113.40	$113.40
Purchase #6	$99.37	12.225%	$111.518	$111.52	$111.50	$111.50
Purchase #7	$245.26	3.271%	$253.2825	$253.28	$253.30	$253.30
7 purchase totals =	$947.27		$1,023.9348	$1,023.93	$1,023.95	$1,024.00