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	$212.87	3.285%	$219.8628	$219.86	$219.85	$219.90
Purchase #2	$146.71	9.565%	$160.7428	$160.74	$160.75	$160.70
Purchase #3	$60.28	12.533%	$67.8349	$67.83	$67.85	$67.80
Purchase #4	$178.60	3.320%	$184.5295	$184.53	$184.55	$184.50
Purchase #5	$145.72	12.523%	$163.9685	$163.97	$163.95	$164.00
Purchase #6	$62.54	5.618%	$66.0535	$66.05	$66.05	$66.10
Purchase #7	$175.32	12.128%	$196.5828	$196.58	$196.60	$196.60
7 purchase totals =	$982.04		$1,059.5748	$1,059.56	$1,059.60	$1,059.60