Calculate the sales tax for a purchase of $45.
The sales tax can vary depending on location, but assuming a sales tax rate of 10%, the sales tax for a purchase of $45 is $4.05.
Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Calculate the sales tax for a purchase of $45.

### Response:
The sales tax can vary depending on location, but assuming a sales tax rate of 10%, the sales tax for a purchase of $45 is $4.05.