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	$203.62	3.753%	$211.2619	$211.26	$211.25	$211.30
Purchase #2	$76.41	7.821%	$82.386	$82.39	$82.40	$82.40
Purchase #3	$78.43	10.420%	$86.6024	$86.60	$86.60	$86.60
Purchase #4	$118.82	11.311%	$132.2597	$132.26	$132.25	$132.30
Purchase #5	$49.48	4.429%	$51.6715	$51.67	$51.65	$51.70
Purchase #6	$103.89	9.292%	$113.5435	$113.54	$113.55	$113.50
Purchase #7	$200.76	4.654%	$210.1034	$210.10	$210.10	$210.10
7 purchase totals =	$831.41		$887.8284	$887.82	$887.80	$887.90