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	$59.27	4.520%	$61.949	$61.95	$61.95	$61.90
Purchase #2	$155.79	6.739%	$166.2887	$166.29	$166.30	$166.30
Purchase #3	$126.40	10.626%	$139.8313	$139.83	$139.85	$139.80
Purchase #4	$215.29	12.435%	$242.0613	$242.06	$242.05	$242.10
Purchase #5	$129.94	5.320%	$136.8528	$136.85	$136.85	$136.90
Purchase #6	$194.34	3.412%	$200.9709	$200.97	$200.95	$201.00
Purchase #7	$62.34	5.366%	$65.6852	$65.69	$65.70	$65.70
7 purchase totals =	$943.37		$1,013.6392	$1,013.64	$1,013.65	$1,013.70