In a report to clients issued Monday afternoon, Piper Jaffray’s Gene Munster offered some quick analysis of the latest U.S. retail data from the NPD Group.

His findings:

• Based on data that show domestic Mac sales up 25% year over year for the past three months, Munster estimates that Apple (AAPL) sold between 2.8 and 2.9 million computers in its second fiscal quarter. He believes the Street’s consensus is about 2.7 million. We put it closer to 3 million (see here).
• NPD data for the past three months has iPod sales up 3% year over year. Extrapolating to include international sales — which for this line is significant — Munster estimates that Apple shipped 9 to 10 million iPods in its second quarter. He puts the consensus at about 9 million; we think the consensus is a bit over 10 million.
• Using Apple’s April 8 announcement that the company had sold “over 50 million iPhones to date” as his starting point, Munster makes an educated guess about what that means: “As a conservative case, if we assume exactly 50.0m iPhones sold to date, this implies unit sales of 6.9m in the March quarter. As an aggressive case, an assumption of 51.0m iPhones sold to date implies unit sales of 7.8m in the March quarter.” He’s going with 7.5 million in his model.

See also:

• U.S. Mac sales up 39% in Jan. and Feb.

[Follow Philip Elmer-DeWitt on Twitter @philiped]