I have dealt with quite a few accountants in my employment and in my contract work for several bookkeeping/accounting services run by accountants. Each one has preferred to keep Sales Discounts separate from a simple reduction in Sales. I would think posting discounts given as a reduction in sales gives a false view of actual sales figures.
Also, depending on whether, at least in Canada, you are operating as a proprietor, partnership, or corporation, you may want to break out discounts given to customers as a separate line item on your income statement rather than simply a reduction in sales. Come tax time or year end review engagements, your accountant can let you know whether or not you are giving TOO MUCH as a discount based upon gross sales and cost of goods.
Personally, I like a LITTLE bit more detail. EG in a construction company, I prefer to keep purchases of small tools (expense), equipment rentals (an obvious expense) or purchase of tools of a material value (eg. a compacting machine costing 3500) separated. This lets me know if I am spending large sums on equipment rentals when it would be more cost efficient to purchase the equipment. EG renting pneumatic drills totalling $4500 for the year when we could have purchased 2 for the same money and been able to use them 2 to
3 years before requiring extensive repairs or replacement.
Just my little bit of hair splitting.