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	$228.96	10.534%	$253.0786	$253.08	$253.10	$253.10
Purchase #2	$222.34	12.187%	$249.4366	$249.44	$249.45	$249.40
Purchase #3	$86.72	4.341%	$90.4845	$90.48	$90.50	$90.50
Purchase #4	$107.54	3.521%	$111.3265	$111.33	$111.35	$111.30
Purchase #5	$71.48	6.834%	$76.3649	$76.36	$76.35	$76.40
Purchase #6	$203.34	5.476%	$214.4749	$214.47	$214.45	$214.50
Purchase #7	$233.96	3.721%	$242.6657	$242.67	$242.65	$242.70
7 purchase totals =	$1,154.34		$1,237.8317	$1,237.83	$1,237.85	$1,237.90