US discounter Dollar General has booked an increase in first-quarter profits but cut the top end of its full-year earnings forecast.

In the three months ended 3 May, net profit was up 5.5% to US$220.1m. Operating profit reached $395m, from $384m last year.

Net sales grew 8.5% in the quarter to $4.23bn, while same-store sales increased 2.6% on the back of increases in both customer traffic and average transaction amount.

The company updated its outlook for the year, citing “moderating” sales growth and a lower expected gross profit rate. It is now expecting $3.15-3.22 per share from an earlier forecast of $3.30.

It sees total sales increasing 10-11% over the 2012 fiscal year. Same-store sales are expected to increase 4-5%.