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	$172.68	8.410%	$187.2024	$187.20	$187.20	$187.20
Purchase #2	$134.38	6.306%	$142.854	$142.85	$142.85	$142.90
Purchase #3	$72.30	6.514%	$77.0096	$77.01	$77.00	$77.00
Purchase #4	$200.78	3.677%	$208.1627	$208.16	$208.15	$208.20
Purchase #5	$150.97	3.619%	$156.4336	$156.43	$156.45	$156.40
Purchase #6	$76.71	8.801%	$83.4612	$83.46	$83.45	$83.50
Purchase #7	$137.83	13.417%	$156.3227	$156.32	$156.30	$156.30
7 purchase totals =	$945.65		$1,011.4462	$1,011.43	$1,011.40	$1,011.50