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	$43.53	3.236%	$44.9386	$44.94	$44.95	$44.90
Purchase #2	$86.46	12.758%	$97.4906	$97.49	$97.50	$97.50
Purchase #3	$241.99	8.262%	$261.9832	$261.98	$262.00	$262.00
Purchase #4	$87.61	13.523%	$99.4575	$99.46	$99.45	$99.50
Purchase #5	$114.74	11.463%	$127.8926	$127.89	$127.90	$127.90
Purchase #6	$249.85	12.602%	$281.3361	$281.34	$281.35	$281.30
Purchase #7	$132.86	5.289%	$139.887	$139.89	$139.90	$139.90
7 purchase totals =	$957.04		$1,052.9856	$1,052.99	$1,053.05	$1,053.00