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	$184.89	11.184%	$205.5681	$205.57	$205.55	$205.60
Purchase #2	$25.47	9.432%	$27.8723	$27.87	$27.85	$27.90
Purchase #3	$214.31	3.873%	$222.6102	$222.61	$222.60	$222.60
Purchase #4	$134.59	5.546%	$142.0544	$142.05	$142.05	$142.10
Purchase #5	$198.92	8.321%	$215.4721	$215.47	$215.45	$215.50
Purchase #6	$141.95	6.263%	$150.8403	$150.84	$150.85	$150.80
Purchase #7	$62.40	7.438%	$67.0413	$67.04	$67.05	$67.00
7 purchase totals =	$962.53		$1,031.4587	$1,031.45	$1,031.40	$1,031.50