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	$195.88	6.646%	$208.8982	$208.90	$208.90	$208.90
Purchase #2	$227.77	7.828%	$245.5998	$245.60	$245.60	$245.60
Purchase #3	$23.93	4.155%	$24.9243	$24.92	$24.90	$24.90
Purchase #4	$96.89	4.217%	$100.9759	$100.98	$101.00	$101.00
Purchase #5	$38.46	6.160%	$40.8291	$40.83	$40.85	$40.80
Purchase #6	$90.52	7.372%	$97.1931	$97.19	$97.20	$97.20
Purchase #7	$25.97	9.617%	$28.4675	$28.47	$28.45	$28.50
7 purchase totals =	$699.42		$746.8879	$746.89	$746.90	$746.90