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	$123.60	7.494%	$132.8626	$132.86	$132.85	$132.90
Purchase #2	$26.90	8.671%	$29.2325	$29.23	$29.25	$29.20
Purchase #3	$56.75	13.695%	$64.5219	$64.52	$64.50	$64.50
Purchase #4	$90.55	11.224%	$100.7133	$100.71	$100.70	$100.70
Purchase #5	$65.98	7.411%	$70.8698	$70.87	$70.85	$70.90
Purchase #6	$119.79	7.366%	$128.6137	$128.61	$128.60	$128.60
Purchase #7	$197.98	3.815%	$205.5329	$205.53	$205.55	$205.50
7 purchase totals =	$681.55		$732.3467	$732.33	$732.30	$732.30