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	$182.38	5.250%	$191.955	$191.96	$191.95	$192.00
Purchase #2	$56.50	11.477%	$62.9845	$62.98	$63.00	$63.00
Purchase #3	$26.40	9.342%	$28.8663	$28.87	$28.85	$28.90
Purchase #4	$233.86	3.297%	$241.5704	$241.57	$241.55	$241.60
Purchase #5	$142.91	6.218%	$151.7961	$151.80	$151.80	$151.80
Purchase #6	$80.32	6.357%	$85.4259	$85.43	$85.45	$85.40
Purchase #7	$234.64	4.381%	$244.9196	$244.92	$244.90	$244.90
7 purchase totals =	$957.01		$1,007.5178	$1,007.53	$1,007.50	$1,007.60