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	$58.52	9.406%	$64.0244	$64.02	$64.00	$64.00
Purchase #2	$93.86	3.329%	$96.9846	$96.98	$97.00	$97.00
Purchase #3	$246.58	4.768%	$258.3369	$258.34	$258.35	$258.30
Purchase #4	$66.94	10.384%	$73.891	$73.89	$73.90	$73.90
Purchase #5	$179.47	11.508%	$200.1234	$200.12	$200.10	$200.10
Purchase #6	$226.53	12.791%	$255.5055	$255.51	$255.50	$255.50
Purchase #7	$224.42	9.540%	$245.8297	$245.83	$245.85	$245.80
7 purchase totals =	$1,096.32		$1,194.6955	$1,194.69	$1,194.70	$1,194.60