aha. Apocolypse.
int Taxrate;
int stands for integer which is a whole number. By inputting 0.1 where an integer is expected it must round down to 0, and anything mutliplied by 0 is 0
Do what Cobo said and change your three variables (I would change all 3) to floating point numbers. This allows a decimal spot.
So now it would be:
float Price;
float Taxrate;
float Tax;
I think you might also need to change:
scanf ("%d", &Price);
scanf ("%d", &Taxrate);
to:
scanf ("%f", &Price);
scanf ("%f", &Taxrate);
and:
printf("%d", Tax);
to:
printf("%f", Tax);
Also Apocolypse, don't just make these changed blindly. Its important to understand why you are making the changes. If* that works and you don't unserstand why it didn't before but does now do some net research or ask