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	$237.31	10.735%	$262.7852	$262.79	$262.80	$262.80
Purchase #2	$176.49	10.748%	$195.4591	$195.46	$195.45	$195.50
Purchase #3	$218.89	8.444%	$237.3731	$237.37	$237.35	$237.40
Purchase #4	$111.88	13.529%	$127.0162	$127.02	$127.00	$127.00
Purchase #5	$105.77	12.615%	$119.1129	$119.11	$119.10	$119.10
Purchase #6	$47.34	9.526%	$51.8496	$51.85	$51.85	$51.80
Purchase #7	$96.64	13.232%	$109.4274	$109.43	$109.45	$109.40
7 purchase totals =	$994.32		$1,103.0235	$1,103.03	$1,103.00	$1,103.00