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	$132.47	13.547%	$150.4157	$150.42	$150.40	$150.40
Purchase #2	$163.34	11.749%	$182.5308	$182.53	$182.55	$182.50
Purchase #3	$117.47	9.714%	$128.881	$128.88	$128.90	$128.90
Purchase #4	$122.53	7.828%	$132.1216	$132.12	$132.10	$132.10
Purchase #5	$120.62	8.674%	$131.0826	$131.08	$131.10	$131.10
Purchase #6	$59.84	4.454%	$62.5053	$62.51	$62.50	$62.50
Purchase #7	$244.46	11.277%	$272.0278	$272.03	$272.05	$272.00
7 purchase totals =	$960.73		$1,059.5648	$1,059.57	$1,059.60	$1,059.50