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	$137.28	9.426%	$150.22	$150.22	$150.20	$150.20
Purchase #2	$31.72	3.517%	$32.8356	$32.84	$32.85	$32.80
Purchase #3	$87.32	4.751%	$91.4686	$91.47	$91.45	$91.50
Purchase #4	$86.94	5.781%	$91.966	$91.97	$91.95	$92.00
Purchase #5	$232.87	11.169%	$258.8793	$258.88	$258.90	$258.90
Purchase #6	$169.79	5.347%	$178.8687	$178.87	$178.85	$178.90
Purchase #7	$231.36	11.850%	$258.7762	$258.78	$258.80	$258.80
7 purchase totals =	$977.28		$1,063.0144	$1,063.03	$1,063.00	$1,063.10