Inflation can be bad. Today, you may store 1$ for a cheap fountain drink at a gas station. Unfortunately, you need to add in inflation. Even if you compensate for a usual tax of 5-10% of what you spend, you still need to account for the future inflation that may happen.
Inflation is caused caused by multiple reasons. Either by demand and supply or accounting for more taxes or any number of other causes, inflation makes what you pay tomorrow higher than what you pay today.