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	$104.40	4.826%	$109.4383	$109.44	$109.45	$109.40
Purchase #2	$234.89	6.270%	$249.6176	$249.62	$249.60	$249.60
Purchase #3	$200.49	7.663%	$215.8535	$215.85	$215.85	$215.90
Purchase #4	$10.30	10.553%	$11.387	$11.39	$11.40	$11.40
Purchase #5	$54.54	13.786%	$62.0589	$62.06	$62.05	$62.10
Purchase #6	$144.64	13.714%	$164.4759	$164.48	$164.50	$164.50
Purchase #7	$202.54	9.440%	$221.6598	$221.66	$221.65	$221.70
7 purchase totals =	$951.80		$1,034.4910	$1,034.50	$1,034.50	$1,034.60