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	$85.50	10.127%	$94.1586	$94.16	$94.15	$94.20
Purchase #2	$62.51	4.819%	$65.5224	$65.52	$65.50	$65.50
Purchase #3	$24.51	12.249%	$27.5122	$27.51	$27.50	$27.50
Purchase #4	$146.90	6.828%	$156.9303	$156.93	$156.95	$156.90
Purchase #5	$189.35	13.102%	$214.1586	$214.16	$214.15	$214.20
Purchase #6	$243.36	11.189%	$270.5896	$270.59	$270.60	$270.60
Purchase #7	$220.97	7.782%	$238.1659	$238.17	$238.15	$238.20
7 purchase totals =	$973.10		$1,067.0376	$1,067.04	$1,067.00	$1,067.10