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	$217.69	5.864%	$230.4553	$230.46	$230.45	$230.50
Purchase #2	$24.82	9.851%	$27.265	$27.27	$27.25	$27.30
Purchase #3	$89.56	8.126%	$96.8376	$96.84	$96.85	$96.80
Purchase #4	$215.50	4.708%	$225.6457	$225.65	$225.65	$225.60
Purchase #5	$146.58	13.174%	$165.8904	$165.89	$165.90	$165.90
Purchase #6	$225.35	7.502%	$242.2558	$242.26	$242.25	$242.30
Purchase #7	$38.50	10.682%	$42.6126	$42.61	$42.60	$42.60
7 purchase totals =	$958.00		$1,030.9624	$1,030.98	$1,030.95	$1,031.00