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	$13.46	10.437%	$14.8648	$14.86	$14.85	$14.90
Purchase #2	$160.46	7.337%	$172.233	$172.23	$172.25	$172.20
Purchase #3	$225.48	13.195%	$255.2321	$255.23	$255.25	$255.20
Purchase #4	$32.32	12.295%	$36.2937	$36.29	$36.30	$36.30
Purchase #5	$81.43	10.556%	$90.0258	$90.03	$90.05	$90.00
Purchase #6	$237.76	9.503%	$260.3543	$260.35	$260.35	$260.40
Purchase #7	$224.55	6.234%	$238.5484	$238.55	$238.55	$238.50
7 purchase totals =	$975.46		$1,067.5521	$1,067.54	$1,067.60	$1,067.50