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	$208.92	6.870%	$223.2728	$223.27	$223.25	$223.30
Purchase #2	$203.41	11.354%	$226.5052	$226.51	$226.50	$226.50
Purchase #3	$162.69	13.684%	$184.9525	$184.95	$184.95	$185.00
Purchase #4	$32.92	4.606%	$34.4363	$34.44	$34.45	$34.40
Purchase #5	$22.49	8.725%	$24.4523	$24.45	$24.45	$24.50
Purchase #6	$191.48	12.371%	$215.168	$215.17	$215.15	$215.20
Purchase #7	$159.66	5.594%	$168.5914	$168.59	$168.60	$168.60
7 purchase totals =	$981.57		$1,077.3785	$1,077.38	$1,077.35	$1,077.50