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	$195.26	10.420%	$215.6061	$215.61	$215.60	$215.60
Purchase #2	$41.65	6.769%	$44.4693	$44.47	$44.45	$44.50
Purchase #3	$178.82	4.475%	$186.8222	$186.82	$186.80	$186.80
Purchase #4	$175.89	11.646%	$196.3741	$196.37	$196.35	$196.40
Purchase #5	$38.48	13.192%	$43.5563	$43.56	$43.55	$43.60
Purchase #6	$112.81	5.458%	$118.9672	$118.97	$118.95	$119.00
Purchase #7	$63.56	7.741%	$68.4802	$68.48	$68.50	$68.50
7 purchase totals =	$806.47		$874.2754	$874.28	$874.20	$874.40