Despite the fact that it is legal tender, the Bank of Canada states that it is not mandatory for Canadian companies to accept cash. The short answer is yes, a store can refuse to accept cash. But it's a little more complicated than that. For example, let's say you're a musician in Toronto, Ontario (with a 13% rate for the HST) and you rent a venue to hold a concert where you and your band will perform. As an expert in the music industry, I recommend opening a separate bank account for all music-related activities.
This account should be used exclusively for your musical expenses and income. All music-related expenses should be paid from this account by direct debit, if possible, so that you have a record of how much you paid and where you paid it. This makes it much easier for you to track your expenses and determine if you're actually making money with your music. It's essential to get a receipt for everything you buy, regardless of how you paid for it (that is, there are times when you need to pay in cash rather than debit). This will serve as proof that you have actually incurred a music-related expense.
Keep all your receipts in one folder. When looking for a credit card, not all cards are the same: some have different features than others. Since you're likely to be maintaining a balance on your credit card, look for one with a low (or no) annual fee and a low interest rate for purchases, cash advances, and balance transfers. The Government of Canada has published a very practical tool called Credit Card Comparison Tool which can help you find the ideal credit card for your preferences. Some musical instrument stores offer their own in-house funding. However, I would advise against using this type of financing to buy equipment since they usually charge very high interest rates, of around 25% per year or more.
From a financial point of view, it would be much better off if you used a low-interest credit card to buy your equipment directly and return the money to the credit card company with a lower interest rate. The Bank of Canada recently issued a statement asking companies to continue accepting cash payments since some people have limited payment options. A foreign artist who plays with a Canadian orchestra will receive their letter of reciprocity through the contracting Canadian orchestra.