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	$127.59	10.460%	$140.9359	$140.94	$140.95	$140.90
Purchase #2	$85.32	4.137%	$88.8497	$88.85	$88.85	$88.80
Purchase #3	$112.85	5.381%	$118.9225	$118.92	$118.90	$118.90
Purchase #4	$113.72	11.707%	$127.0332	$127.03	$127.05	$127.00
Purchase #5	$91.66	12.161%	$102.8068	$102.81	$102.80	$102.80
Purchase #6	$24.63	8.611%	$26.7509	$26.75	$26.75	$26.80
Purchase #7	$118.56	8.168%	$128.244	$128.24	$128.25	$128.20
7 purchase totals =	$674.33		$733.5430	$733.54	$733.55	$733.40