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	$231.82	13.390%	$262.8607	$262.86	$262.85	$262.90
Purchase #2	$124.95	4.359%	$130.3966	$130.40	$130.40	$130.40
Purchase #3	$175.25	3.696%	$181.7272	$181.73	$181.75	$181.70
Purchase #4	$70.43	10.177%	$77.5977	$77.60	$77.60	$77.60
Purchase #5	$49.95	4.399%	$52.1473	$52.15	$52.15	$52.10
Purchase #6	$153.37	9.868%	$168.5046	$168.50	$168.50	$168.50
Purchase #7	$168.25	11.564%	$187.7064	$187.71	$187.70	$187.70
7 purchase totals =	$974.02		$1,060.9405	$1,060.95	$1,060.95	$1,060.90