Sales have continued rising and margins have been maintained since JD Sports Fashion's last update in September, the trendy sportswear retailer said today.The company added that its result for the full year depends on sales and margins in December and January.'We are inevitably cautious about maintaining such positive like for like sales performance during the Christmas period against a backdrop of successive uplifts in previous years,' the company said.JD Sports saw pre-tax profits rise to £16.6m in the 26 weeks to July from £10.1m in the same period the previous year as sales jumped 18.5% to £384m.Its fortunes are in contrast to fellow sportswear group JJB Sports which hit a year-low earlier last week after a promotional push failed to lift sales.