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	$205.42	5.384%	$216.4798	$216.48	$216.50	$216.50
Purchase #2	$222.83	4.789%	$233.5013	$233.50	$233.50	$233.50
Purchase #3	$101.71	13.692%	$115.6361	$115.64	$115.65	$115.60
Purchase #4	$141.41	13.759%	$160.8666	$160.87	$160.85	$160.90
Purchase #5	$177.35	13.116%	$200.6112	$200.61	$200.60	$200.60
Purchase #6	$123.87	7.805%	$133.5381	$133.54	$133.55	$133.50
Purchase #7	$11.31	9.824%	$12.4211	$12.42	$12.40	$12.40
7 purchase totals =	$983.90		$1,073.0542	$1,073.06	$1,073.05	$1,073.00