CODEWITHSUNDEEP
c#vb.net
ewitkows
ewitkows

Reputation: 3618

Round decimal value to nearest 5 or 0 amount

I have a web application that will apply a percentage markup to a product, but the percentage will be specified by a user. For example, the user can indicate they want to mark up a product 5%, 9%, 23%, etc. My problem is, the product price will change as well, and in doing so, end up giving ugly values ($1462.72)

As a result, my users are hoping that we can round the value to the nearest 5\0 value. So if my marked up product price is $1462.72, it would round up to $1465. $1798.02 on the other hand would round up to an even $1800.

Using VB\C#, how can I go about rounding these values?

Thanks!

Upvotes: 1

Views: 3307

Answers (2)

D Stanley
D Stanley

Reputation: 152566

To round to an arbitrary modulus you can create a function like:

public decimal Round(decimal source, decimal modulus)
{
    return (Math.Round(source / modulus) * modulus);
}

and use it in this way:

decimal rounded = Round(1798.02m , 5.0m);  // yields 1800.0
decimal rounded = Round(1462.72m , 5.0m);  // yields 1465.0
decimal rounded = Round(2481.23m , 5.0m);  // yields 2480.0

Note that Math.Round by default rounds midpoint values to the closest even number (e.g. 1.5 and 2.5 would both "round" to 2. In your case, the effect is that any numbers that are exactly between a 0 and 5 number (i.e. 2.5, 7.5) would be rounded to the closest 10:

decimal rounded = Round(1697.50m , 5.0m);  // yields 1700.0
decimal rounded = Round(1702.50m , 5.0m);  // yields 1700.0

If you want to always round UP on the midpoint just specify that in Round:

return (Math.Round(source / modulus, MidpointRounding.AwayFromZero) * modulus);

Upvotes: 11

yoozer8
yoozer8

Reputation: 7489

You can use the modulus operator to calculate the adjustment needed.

decimal price = 1798.02;
decimal adjustment = price % 5.0;
if(adjustment != 0) //so we don't round up already round numbers
{
  price = (price - adjustment) + 5;
}

This will bring it up to the next multiple of 5.

Upvotes: 1

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