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	$166.69	11.498%	$185.856	$185.86	$185.85	$185.90
Purchase #2	$188.72	5.541%	$199.177	$199.18	$199.20	$199.20
Purchase #3	$213.49	9.752%	$234.3095	$234.31	$234.30	$234.30
Purchase #4	$128.74	4.121%	$134.0454	$134.05	$134.05	$134.00
Purchase #5	$166.80	3.631%	$172.8565	$172.86	$172.85	$172.90
Purchase #6	$63.29	5.587%	$66.826	$66.83	$66.85	$66.80
Purchase #7	$59.50	13.575%	$67.5771	$67.58	$67.60	$67.60
7 purchase totals =	$987.23		$1,060.6475	$1,060.67	$1,060.70	$1,060.70