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	$181.63	8.493%	$197.0558	$197.06	$197.05	$197.10
Purchase #2	$90.50	13.137%	$102.389	$102.39	$102.40	$102.40
Purchase #3	$31.25	13.593%	$35.4978	$35.50	$35.50	$35.50
Purchase #4	$100.37	13.404%	$113.8236	$113.82	$113.80	$113.80
Purchase #5	$151.49	13.771%	$172.3517	$172.35	$172.35	$172.40
Purchase #6	$78.88	3.296%	$81.4799	$81.48	$81.50	$81.50
Purchase #7	$57.31	10.685%	$63.4336	$63.43	$63.45	$63.40
7 purchase totals =	$691.43		$766.0314	$766.03	$766.05	$766.10