Not quite. .05 cents is five one-hundredths of a cent, or 1/20th. One-half of one cent is 0.5 cents, or 5/10. But not here to quibble with a possible typo.
Your statement assuming $15/hour is low. You are neglecting employer-paid payroll taxes. Social Security and Medicare taxes are 7.65%, or another $1.15/hour. If these are new employees to Tesla, there is also federal and state unemployment insurance paid on the first $7,000 of annual pay. The federal rate is low, 0.6%, but the state rate can be as high as 6.2% depending upon Tesla's unemployment claims from terminated employees. Let's run with a 6% total. That's another 90 cents per hour. Then there is workman's compensation. I have no idea how Tesla would categorize these valet persons, but let's say that the unadjusted manual rate for this sort of work is $5/$100 of payroll, or 5%. Another six bits. Perhaps Tesla would draw upon existing employees instead who are not normally scheduled. This might cost overtime premium for those people who come to work on their days off or who clock in early or clock out late. This is unknown, of course. Or, maybe Tesla contracts with a security company to send contracted employees to perform this function. The security company is going to mark up the actual costs of these valets by about 35% to cover its overhead and profit.
Cheapest case would be $15.00+$1.15+$.90+$.75 = $17.80, disregarding compensated absences if these people work elsewhere for Tesla.
It could only increase from there depending upon the technique that Tesla chooses to fulfill this role.
This analysis also ignores possible liability issues if the valet damages one or more vehicles while moving the cars about.