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	$238.88	11.822%	$267.1204	$267.12	$267.10	$267.10
Purchase #2	$53.65	10.196%	$59.1202	$59.12	$59.10	$59.10
Purchase #3	$59.72	12.847%	$67.3922	$67.39	$67.40	$67.40
Purchase #4	$96.40	8.613%	$104.7029	$104.70	$104.70	$104.70
Purchase #5	$86.86	13.288%	$98.402	$98.40	$98.40	$98.40
Purchase #6	$211.84	11.735%	$236.6994	$236.70	$236.70	$236.70
Purchase #7	$241.98	4.331%	$252.4602	$252.46	$252.45	$252.50
7 purchase totals =	$989.33		$1,085.8973	$1,085.89	$1,085.85	$1,085.90