Round up values

hii friends,

i need exact formula for:
@B column
1) if my resulting value is above 0.25 , then round off to 0.5.( example my cell result values is 6.33 then roundup to 6.50)
2)if below or equal to 0.25 then round down to 0.00 (for example my cell result values is 4.25 then roundup to 4.00)@B column

@D column:
1) if my resulting value is above 0.6 , then round off to 1.0.( example my cell result values is 8.71 then roundup to 9.00)
2)if my resulting value is between 0.26 and 0.59 , then round off to 0.5.( example my cell result values is 6.33 then roundup to 6.50)
3) if my resulting value is between 0.01 and 0.29, then round off to 0.00.( example my cell result values is 5.25 then round down to 5.00)

please apply to my sample workbook.