How to correctly choose the data type for storing cost considering kopecks in the system?

To store monetary values with cents, it is important to choose a data type that ensures accuracy and avoids rounding errors.

Common approaches include:

• Integer types — store the amount in the smallest units (e.g., cents). Instead of 123.45 rubles, store 12345 (an integer). This eliminates rounding errors in arithmetic.

• Fixed-point decimal types (e.g., decimal or big.Rat in Go) — allow working with numbers with a fixed number of decimal places.

In Go, for financial calculations, it is common to use integer values or third-party libraries for decimal arithmetic, such as shopspring/decimal:

import "github.com/shopspring/decimal"

price := decimal.NewFromFloat(123.45)
// operations with precise decimal arithmetic

Thus, the choice depends on the requirements for accuracy and ease of working with monetary values.