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	$145.80	5.867%	$154.3541	$154.35	$154.35	$154.40
Purchase #2	$38.82	6.342%	$41.282	$41.28	$41.30	$41.30
Purchase #3	$215.68	13.341%	$244.4539	$244.45	$244.45	$244.50
Purchase #4	$139.92	4.789%	$146.6208	$146.62	$146.60	$146.60
Purchase #5	$217.63	10.689%	$240.8925	$240.89	$240.90	$240.90
Purchase #6	$8.60	8.786%	$9.3556	$9.36	$9.35	$9.40
Purchase #7	$246.60	4.765%	$258.3505	$258.35	$258.35	$258.40
7 purchase totals =	$1,013.05		$1,095.3094	$1,095.30	$1,095.30	$1,095.50