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	$117.64	8.526%	$127.67	$127.67	$127.65	$127.70
Purchase #2	$135.60	11.228%	$150.8252	$150.83	$150.85	$150.80
Purchase #3	$162.35	7.230%	$174.0879	$174.09	$174.10	$174.10
Purchase #4	$103.96	8.615%	$112.9162	$112.92	$112.90	$112.90
Purchase #5	$51.60	13.323%	$58.4747	$58.47	$58.45	$58.50
Purchase #6	$146.51	12.508%	$164.8355	$164.84	$164.85	$164.80
Purchase #7	$225.45	9.336%	$246.498	$246.50	$246.50	$246.50
7 purchase totals =	$943.11		$1,035.3075	$1,035.32	$1,035.30	$1,035.30