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	$203.71	9.272%	$222.598	$222.60	$222.60	$222.60
Purchase #2	$18.72	11.393%	$20.8528	$20.85	$20.85	$20.90
Purchase #3	$9.93	6.260%	$10.5516	$10.55	$10.55	$10.60
Purchase #4	$197.57	10.126%	$217.5759	$217.58	$217.60	$217.60
Purchase #5	$83.78	3.109%	$86.3847	$86.38	$86.40	$86.40
Purchase #6	$237.38	12.753%	$267.6531	$267.65	$267.65	$267.70
Purchase #7	$182.48	8.583%	$198.1423	$198.14	$198.15	$198.10
7 purchase totals =	$933.57		$1,023.7584	$1,023.75	$1,023.80	$1,023.90