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	$167.33	5.452%	$176.4528	$176.45	$176.45	$176.50
Purchase #2	$233.25	9.710%	$255.8986	$255.90	$255.90	$255.90
Purchase #3	$86.83	13.355%	$98.4261	$98.43	$98.45	$98.40
Purchase #4	$159.37	12.139%	$178.7159	$178.72	$178.70	$178.70
Purchase #5	$203.75	3.813%	$211.519	$211.52	$211.50	$211.50
Purchase #6	$190.97	13.256%	$216.285	$216.29	$216.30	$216.30
Purchase #7	$62.40	7.137%	$66.8535	$66.85	$66.85	$66.90
7 purchase totals =	$1,103.90		$1,204.1509	$1,204.16	$1,204.15	$1,204.20