Domino's Pizza shrugged off weak economic conditions to post a 9.8% rise in sales in the 13 weeks to 25 September.The pizza deliverer's sales during the period climbed to £127m from £115.7m, bringing sales for the year to date so far up to £385.4m, a 9.2% rise from £352.8m the previous year.Like-for-like sales in the 13 week period were up by 3.9%, compared with growth of 9.9% in the previous period.Domino's said trading remains tough in the Republic of Ireland."We are pleased to have had a good quarter's trading and, although the economy as a whole is still very tough, we have got exciting plans in place for the rest of the year," said chief executive Chris Moore. "We are on track and confident that we will finish the year in line with market expectations." The shares fell heavily on the results, and were trading at 464p over the lunch-time session, down 44p.---RG