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	$230.37	4.635%	$241.0476	$241.05	$241.05	$241.00
Purchase #2	$211.35	5.443%	$222.8538	$222.85	$222.85	$222.90
Purchase #3	$94.40	10.465%	$104.279	$104.28	$104.30	$104.30
Purchase #4	$35.51	5.103%	$37.3221	$37.32	$37.30	$37.30
Purchase #5	$18.56	4.768%	$19.4449	$19.44	$19.45	$19.40
Purchase #6	$133.59	11.785%	$149.3336	$149.33	$149.35	$149.30
Purchase #7	$172.53	11.828%	$192.9368	$192.94	$192.95	$192.90
7 purchase totals =	$896.31		$967.2178	$967.21	$967.25	$967.10