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	$167.86	4.706%	$175.7595	$175.76	$175.75	$175.80
Purchase #2	$188.44	9.233%	$205.8387	$205.84	$205.85	$205.80
Purchase #3	$201.57	10.523%	$222.7812	$222.78	$222.80	$222.80
Purchase #4	$24.26	11.474%	$27.0436	$27.04	$27.05	$27.00
Purchase #5	$117.42	5.271%	$123.6092	$123.61	$123.60	$123.60
Purchase #6	$97.49	12.150%	$109.335	$109.34	$109.35	$109.30
Purchase #7	$182.41	4.511%	$190.6385	$190.64	$190.65	$190.60
7 purchase totals =	$979.45		$1,055.0057	$1,055.01	$1,055.05	$1,054.90