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	$85.69	11.298%	$95.3713	$95.37	$95.35	$95.40
Purchase #2	$186.26	9.866%	$204.6364	$204.64	$204.65	$204.60
Purchase #3	$43.79	9.716%	$48.0446	$48.04	$48.05	$48.00
Purchase #4	$137.53	13.628%	$156.2726	$156.27	$156.25	$156.30
Purchase #5	$54.38	5.673%	$57.465	$57.47	$57.45	$57.50
Purchase #6	$56.80	4.812%	$59.5332	$59.53	$59.55	$59.50
Purchase #7	$103.28	8.499%	$112.0578	$112.06	$112.05	$112.10
7 purchase totals =	$667.73		$733.3809	$733.38	$733.35	$733.40