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	$101.29	4.419%	$105.766	$105.77	$105.75	$105.80
Purchase #2	$143.67	5.516%	$151.5948	$151.59	$151.60	$151.60
Purchase #3	$205.98	13.385%	$233.5504	$233.55	$233.55	$233.60
Purchase #4	$198.61	9.164%	$216.8106	$216.81	$216.80	$216.80
Purchase #5	$163.25	13.207%	$184.8104	$184.81	$184.80	$184.80
Purchase #6	$176.53	4.380%	$184.262	$184.26	$184.25	$184.30
Purchase #7	$25.88	6.175%	$27.4781	$27.48	$27.50	$27.50
7 purchase totals =	$1,015.21		$1,104.2723	$1,104.27	$1,104.25	$1,104.40