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	$156.34	7.209%	$167.6106	$167.61	$167.60	$167.60
Purchase #2	$16.65	12.667%	$18.7591	$18.76	$18.75	$18.80
Purchase #3	$69.52	13.387%	$78.8266	$78.83	$78.85	$78.80
Purchase #4	$93.83	7.712%	$101.0662	$101.07	$101.05	$101.10
Purchase #5	$11.36	7.797%	$12.2457	$12.25	$12.25	$12.20
Purchase #6	$156.67	11.723%	$175.0364	$175.04	$175.05	$175.00
Purchase #7	$157.55	3.120%	$162.4656	$162.47	$162.45	$162.50
7 purchase totals =	$661.92		$716.0102	$716.03	$716.00	$716.00