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	$83.93	13.166%	$94.9802	$94.98	$95.00	$95.00
Purchase #2	$96.37	5.420%	$101.5933	$101.59	$101.60	$101.60
Purchase #3	$114.88	13.716%	$130.6369	$130.64	$130.65	$130.60
Purchase #4	$16.60	12.349%	$18.6499	$18.65	$18.65	$18.60
Purchase #5	$82.59	9.461%	$90.4038	$90.40	$90.40	$90.40
Purchase #6	$121.89	10.487%	$134.6726	$134.67	$134.65	$134.70
Purchase #7	$87.94	12.531%	$98.9598	$98.96	$98.95	$99.00
7 purchase totals =	$604.20		$669.8965	$669.89	$669.90	$669.90