Dictionary with a running total - dictionary

Question

This is for a homework I am doing.
I have a .txt file that looks like this.
11
eggs
1.17
milk
3.54
bread
1.50
coffee
3.57
sugar
1.07
flour
1.37
apple
.33
cheese
4.43
orange
.37
bananas
.53
potato
.19
What I'm trying to do is keep a running total, when you type in the word "Eggs" then the word "bread" it needs to add the cost of both and keep going until "EXIT" also I'm going to run into a 'KeyError' and need help with that also.
def main():
key = ''
infile = open('shoppinglist.txt', 'r')
total = 0
count = infile.readline()
grocery = ''
groceries = {}
print('This program keeps a running total of your shopping list.')
print('Use \'EXIT\' to exit.')
while grocery != 'EXIT':
grocery = input('Enter an item: ')
for line in infile:
line = line.strip()
if key == '':
key = line
else:
groceries[key] = line
key = ''
print ('Your current total is $'+ groceries[grocery])
main()

Answer 1

Does the file contain the prices of each of the different groceries?
The user input statement should have a .strip() at the end too as sometimes line ending characters can be included from user input.
You should only need to read the file once, not in the loop.
When the user enters a grocery item it should as you say check that it exists:
if grocery in groceries:
...
else:
#grocery name not recognised
I think you should have a separate dictionary to store the counts of each grocery something like this: http://docs.python.org/library/collections.html#collections.Counter
import collections
quantitiesWanted = collections.Counter()
Then any grocery can be asked for like this quantitiesWanted['eggs'] which will return 0 by default. Doing something like quantitiesWanted['eggs'] += 1 will increase it to 1 and so on.
To get the current total you can do:
total = 0
for key, value in quantitiesWanted:
total += groceries[key] * value