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	$82.42	12.772%	$92.9467	$92.95	$92.95	$92.90
Purchase #2	$193.34	6.796%	$206.4794	$206.48	$206.50	$206.50
Purchase #3	$228.67	4.365%	$238.6514	$238.65	$238.65	$238.70
Purchase #4	$167.42	3.367%	$173.057	$173.06	$173.05	$173.10
Purchase #5	$97.55	8.430%	$105.7735	$105.77	$105.75	$105.80
Purchase #6	$109.32	10.522%	$120.8227	$120.82	$120.80	$120.80
Purchase #7	$127.30	3.565%	$131.8382	$131.84	$131.85	$131.80
7 purchase totals =	$1,006.02		$1,069.5689	$1,069.57	$1,069.55	$1,069.60