iterating by list formulating outline lines fly

edit: i missed essential point: .net 2.0

consider box where i have list unsorted items, effect probity form this:

class testclass
{
    datetime sometime;
    decimal someprice;

    // constructor
}

i need emanate report-like output, where sum prices any accumulated. there should line any item, folled suitable outline lines.

take exam data:

list<testclass> testlist = new list<testclass> { 
new testclass(new datetime(2008,01,01), 12),
new testclass(new datetime(2007,01,01), 20),
new testclass(new datetime(2008,01,01), 18)
};

the preferred cost something this:

2007-01-01: 
20
total: 20

2008-01-01: 
12
18
total: 30

what's best proceed approach such scenarios? box such list, i exercise icomparable interface testclass, list sorted.

to emanate news itself, something used (let's assume have methods tasks accumulating prices, retaining lane tide date etc):

for (int i=0;i<testlist.count;i++)
{
    (isnewdate(testlist[i]))
    {
        createsummaryline();
        resetvaluesfornewdate();
    }

    addvalues(testlist[i]);
}

// final outline line indispensable consolidate information final integrate items.
createsummaryline();

this works alright, nonetheless i have uncanny feeling distant second "createsummarylines" concerned.

in ways hoop such situations (especially deliberation fact, need work list<> equipment rather pre-categorized collection something that)?