Cambridge, MA–Total spending online spending increased from $3.4 billion in February to $3.5 billion in March, according to the most recent online retail survey by research firm Forrester Research, in conjunction with Greenfield Online. While the study concluded that the number of households shopping online in March remained the same–at roughly 13.5 million–consumers spent an average of $263 per person last month, compared to $248 in February. Among the top categories were computer hardware ($400.4 million), consumer electronics ($207.2 million), apparel ($177.5 million), and books ($147.9 million).