Do you want to loop through the table and where ever you find choclate/bun/cake by 10 and where you find biscuit..increase the price by 5?
You can do it in 2ways.
1.Write update statements which will update all the corresponding rows.
update #tempTable set price =price+ 10 where productname in ('Choclate','Bun','Cake');
update #tempTable set price =price+ 5 where productname='Biscuit'
2. Loop through the table using a cursor and update the table accoridingly row by row.
See the below example
DECLARE vendor_cursor CURSOR FOR
SELECT BusinessEntityID, Name
FROM PurchasingVendor;
OPEN vendor_cursor;
FETCH NEXT FROM vendor_cursor
INTO @vendor_id, @vendor_name;
WHILE @@FETCH_STATUS = 0
BEGIN
..... Do your updates here
Hope this helps.