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	$41.83	8.667%	$45.4554	$45.46	$45.45	$45.50
Purchase #2	$150.74	9.667%	$165.312	$165.31	$165.30	$165.30
Purchase #3	$196.62	9.396%	$215.0944	$215.09	$215.10	$215.10
Purchase #4	$55.52	13.684%	$63.1174	$63.12	$63.10	$63.10
Purchase #5	$87.46	10.417%	$96.5707	$96.57	$96.55	$96.60
Purchase #6	$205.49	12.852%	$231.8996	$231.90	$231.90	$231.90
Purchase #7	$231.64	13.794%	$263.5924	$263.59	$263.60	$263.60
7 purchase totals =	$969.30		$1,081.0419	$1,081.04	$1,081.00	$1,081.10