Trying to find a value, if not find first empty cell

I have a workbook I'm working on for our IT inventory.
I need it to look for the value of ItemName. If it finds it, move one cell to the right and add the value entered by the user to the existing value in that cell.
If it doesn't find an equal value for ItemName, I need it to find the first empty cell in column A, then input all 3 values entered by the user:
ItemName
Qty
Location

I can't get it to go past looking for a duplicate ItemName.
Link to download the file:
Here

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I tried this, but it's not quite doing what it's supposed to:

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I missed that part of the mess.
I figured if we just keep adding data to the Data Entry sheet, which is how this was first set up (and working), then the file size would grow out of control.
It does need to evaluate where the new inventory is going (Cabinet #), so it will need to check. I'm just not sure yet how to format the sheet in order to accommodate that.

I think I'm trying to make this more complicated than it needs to be.
Since I'm adding the functionality to add new inventory, I guess I just need to search for an existing ItemName.
But, it still needs to accurately search down column A to find a duplicate for ItemName so it can accurately update the totals.

And I was just looking at the sheet. Yeah, I need to use a different column for each cabinet. Thank ya!

Thank you, very much. After using your code, I figured out that I wouldn't need the Data Entry sheet. I could just use the Totals sheet for what I had going on with the Data Entry sheet.
So far, it's working perfectly. But we'll see how it goes after some tries.

Well, mehmetcik, everything works like a charm, and much simpler code than I had. Thank you again, so very much.