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	$114.94	10.563%	$127.0811	$127.08	$127.10	$127.10
Purchase #2	$93.71	11.312%	$104.3105	$104.31	$104.30	$104.30
Purchase #3	$63.68	13.606%	$72.3443	$72.34	$72.35	$72.30
Purchase #4	$138.31	7.279%	$148.3776	$148.38	$148.40	$148.40
Purchase #5	$236.42	3.464%	$244.6096	$244.61	$244.60	$244.60
Purchase #6	$234.89	3.538%	$243.2004	$243.20	$243.20	$243.20
Purchase #7	$215.86	9.547%	$236.4682	$236.47	$236.45	$236.50
7 purchase totals =	$1,097.81		$1,176.3917	$1,176.39	$1,176.40	$1,176.40