Strong growth online and new store openings helped Dunelm deliver a 14% increase in sales in the first half, as the homeware retailer lifted its interim dividend by 10% and announced a special dividend.Revenues totalled £406.4m in the six months to 27 December 2014, up from £356.4m the year before.Like-for-like growth came in at 6.2% picking up from the 2.1% increase seen for the previous financial year.The company, which opened six new superstores in the first half, said it also saw significant growth online with home delivery sales up 76%.Gross margins were maintained at 50.4%, while pre-tax profit improved 10.7% to £68.2m."Our focus is now emphatically on growth, the early results of which can be seen in the first-half performance," said chief executive Will Adderley.Dunelm increased its interim dividend to 5.5p per share, from 5p the year before, and proposed a special distribution of 70p. The company also said that further special dividends would be paid if net debt stays consistently below the ratio of 0.25 times operating profits.A further six more new shops are planned for the second half from the current level of 148 as the company works towards its goal of operating from 200 stores."We have set ourselves a new, medium-term goal of growing sales by 50%, with half of this coming from stores - improving sales densities in existing stores and rolling out new ones - and the balance coming from growth in the home delivery channel, including increased penetration in furniture," Adderley said.The stock was up 4.4% at 905.38p on Wednesday morning.