My preferred method.
1) Have one or two players buy up all the lowest chips in play in quantity of the next lowest chips. (Buy all 25s in quantities of 100.)
2) Odd chips should be set forward. Deal one card for each odd chip.
3) Exchange the odd chips with one of the players that was collecting for a quantity of the next lowest chip in play. (8 twenty-fives become two hundreds, etc...) If the quantity isn't exact, round to the nearest increment of the next chip. (Round 225 to 200, 250 or 275 to 300.)
4) Award up to one chip per player according to the cards dealt in step 2.
5) have the players holding the chips to be remove add enough other small chips to make a large denomination (1000 when coloring 25s or 100s.) And exchange with the bank.
This method minimizes rounding error and prevents adding chips of denominations that will just be colored up in the future anyway. (Which I know
@BGinGA appreciates

.)
Bottom line:
*Centralize the chips to be removed.
*Make change and award race winners with chips already on the table.
*Only exchange chips with the bank with one or two players per table.
Hope that helps, best I could do typing on my phone.