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	$195.94	10.661%	$216.8292	$216.83	$216.85	$216.80
Purchase #2	$190.45	6.639%	$203.094	$203.09	$203.10	$203.10
Purchase #3	$74.38	10.822%	$82.4294	$82.43	$82.45	$82.40
Purchase #4	$129.60	10.309%	$142.9605	$142.96	$142.95	$143.00
Purchase #5	$160.66	13.719%	$182.7009	$182.70	$182.70	$182.70
Purchase #6	$194.76	10.667%	$215.535	$215.54	$215.55	$215.50
Purchase #7	$38.78	12.125%	$43.4821	$43.48	$43.50	$43.50
7 purchase totals =	$984.57		$1,087.0311	$1,087.03	$1,087.10	$1,087.00