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	$114.42	9.438%	$125.219	$125.22	$125.20	$125.20
Purchase #2	$37.73	9.695%	$41.3879	$41.39	$41.40	$41.40
Purchase #3	$130.95	6.836%	$139.9017	$139.90	$139.90	$139.90
Purchase #4	$83.56	10.105%	$92.0037	$92.00	$92.00	$92.00
Purchase #5	$103.96	12.150%	$116.5911	$116.59	$116.60	$116.60
Purchase #6	$239.45	3.407%	$247.6081	$247.61	$247.60	$247.60
Purchase #7	$180.69	10.826%	$200.2515	$200.25	$200.25	$200.30
7 purchase totals =	$890.76		$962.9630	$962.96	$962.95	$963.00