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	$141.66	10.600%	$156.676	$156.68	$156.70	$156.70
Purchase #2	$222.47	10.298%	$245.38	$245.38	$245.40	$245.40
Purchase #3	$57.77	9.233%	$63.1039	$63.10	$63.10	$63.10
Purchase #4	$71.89	13.186%	$81.3694	$81.37	$81.35	$81.40
Purchase #5	$211.25	5.602%	$223.0842	$223.08	$223.10	$223.10
Purchase #6	$144.60	12.797%	$163.1045	$163.10	$163.10	$163.10
Purchase #7	$169.31	5.616%	$178.8184	$178.82	$178.80	$178.80
7 purchase totals =	$1,018.95		$1,111.5364	$1,111.53	$1,111.55	$1,111.60