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	$217.94	10.786%	$241.447	$241.45	$241.45	$241.40
Purchase #2	$54.88	8.232%	$59.3977	$59.40	$59.40	$59.40
Purchase #3	$91.57	12.813%	$103.3029	$103.30	$103.30	$103.30
Purchase #4	$20.66	12.229%	$23.1865	$23.19	$23.20	$23.20
Purchase #5	$150.40	13.727%	$171.0454	$171.05	$171.05	$171.00
Purchase #6	$204.55	9.774%	$224.5427	$224.54	$224.55	$224.50
Purchase #7	$224.54	8.162%	$242.867	$242.87	$242.85	$242.90
7 purchase totals =	$964.54		$1,065.7892	$1,065.80	$1,065.80	$1,065.70