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	$174.60	11.165%	$194.0941	$194.09	$194.10	$194.10
Purchase #2	$87.55	7.783%	$94.364	$94.36	$94.35	$94.40
Purchase #3	$244.54	9.295%	$267.27	$267.27	$267.25	$267.30
Purchase #4	$117.56	8.426%	$127.4656	$127.47	$127.45	$127.50
Purchase #5	$9.67	12.176%	$10.8474	$10.85	$10.85	$10.80
Purchase #6	$127.36	13.417%	$144.4479	$144.45	$144.45	$144.40
Purchase #7	$239.31	13.857%	$272.4712	$272.47	$272.45	$272.50
7 purchase totals =	$1,000.59		$1,110.9602	$1,110.96	$1,110.90	$1,111.00