Preparing for the euro in France

French banker Loic Pajot checks a new euro bank note in the strongroom of the Banque National of Paris in Nice

By CNN's Hala Gorani

PARIS, France (CNN) -- It's the biggest currency switchover in history -- a difficult and sometimes complicated economic revolution for the eurozone's millions of companies.

Because the euro has been the official corporate accounting currency for two years, it's businesses that thrive on cash transactions that will likely have to adapt the most.

In a matter of days, every store, restaurant owner and corner shop in the eurozone will have to use euros.

It will be a major logistical headache for large retailers like Printemps in France. The company put its 4,000 salespeople through intensive training programs for months.

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"We just finished the training session now and they are more comfortable with these notes and money," says Sylvie Roisne of Printemps. "The major difficulty will be from the 2nd of January until the 16th of February. ... We will receive francs and we will give back euro."

All the training, dual price tags and special tills cost money.

"There have been a lot of implications because you talk about systems, trainings, staff, additional staff, additional tilling," says Jean-Claude Bonnel, director of Printemps.

"So all the elements put together, it's going to be quite a substantial amount at the end of the day."

But it's not only large retailers like Printemps or Galeries Lafayette that need to prepare for the euro; it's also all the smaller corner shops: the local restaurant, the launderette down the road -- even neighbourhood bakeries.

Those are the businesses most likely to suffer most from converting to the euro, including time lost making change at cash registers.

"If you're a small boulangerie, if you have only one shop, it's probably going to be a bigger problem for you," says the manager of Le Moulin de la Vierge.

"Either you're going to work more, plus you're going to have all these investments for the cash registers, plus all the time you're going to lose. ... You lose money when you lose time."

There are hundreds of thousands of cash transactions every day in Europe.

It's estimated that in the first few months, a cash transaction in a bakery will take 40 percent longer with euros than with francs.