There are a few reasons in general why you might want to decline a gift from a boss:

1. The gift carries an implication that something is expected in return, something which is outside the normal boundaries of your job. For example, he might expect that you give priority to his work projects, or give him a favourable review (where employees can review their bosses). Or there is an expectation that you do something like fix his personal computer for him. This doesn't sound like your case.
2. You are being treated significantly different from other employees. If you are being given gifts and others are not, then issues of favouritism can arise, and there may be a perception of bias or reciprocal favours, even if it is not happening. You don't talk about this, so there is no way of knowing if it is happening.
3. The gifts are large enough to be inappropriate. You should certainly decline a gift of a car, or a vacation. This doesn't sound excessive to me, but it may depend on your culture.

If none of these apply, and there is no other significant specific concern you are worried about, then accept the gift and be grateful.

There are a few reasons in general why you might want to decline a gift from a boss:

1. The gift carries an implication that something is expected in return, something which is outside the normal boundaries of your job. For example, he might expect that you give priority to his work projects, or give him a favourable review (where employees can review their bosses). Or there is an expectation that you do something like fix his personal computer for him. This doesn't sound like your case.
2. You are being treated significantly different from other employees. If you are being given gifts and others are not, then issues of favouritism can arise, and there may be a perception of bias or reciprocal favours, even if it is not happening. You don't talk about this, so there is no way of knowing if it is happening.
3. The gifts are large enough to be inappropriate. You should certainly decline a gift of a car, or a vacation. This doesn't sound excessive to me, but it may depend on your culture.

The reason for declining an inappropriately large gift is that they create the impression of something being expected in return. It's the same reason that a politician is OK accepting a monogrammed golf ball from a businessman, but not a new house.

If none of these apply, and there is no other significant specific concern you are worried about, then accept the gift and be grateful.

Note that this answer assumes the gift is from your boss personally, not the company, and that it's not a reward for some achievement.

There are a few reasons in general why you might want to decline a gift from a boss:

1. The gift carries an implication that something is expected in return, something which is outside the normal boundaries of your job. For example, he might expect that you give priority to his work projects, or give him a favourable review (where employees can review their bosses). Or there is an expectation that you do something like fix his personal computer for him. This doesn't sound like your case.
2. You are being treated significantly different from other employees. If you are being given gifts and others are not, then issues of favouritism can arise, and there may be a perception of bias or reciprocal favours, even if it is not happening. You don't talk about this, so there is no way of knowing if it is happening.
3. The gifts are large enough to be inappropriate. You should certainly decline a gift of a car, or a vacation. This doesn't sound excessive to me, but it may depend on your culture.

If none of those apply, then accept the gift and be grateful.

There are a few reasons in general why you might want to decline a gift from a boss:

1. The gift carries an implication that something is expected in return, something which is outside the normal boundaries of your job. For example, he might expect that you give priority to his work projects, or give him a favourable review (where employees can review their bosses). Or there is an expectation that you do something like fix his personal computer for him. This doesn't sound like your case.
2. You are being treated significantly different from other employees. If you are being given gifts and others are not, then issues of favouritism can arise, and there may be a perception of bias or reciprocal favours, even if it is not happening. You don't talk about this, so there is no way of knowing if it is happening.
3. The gifts are large enough to be inappropriate. You should certainly decline a gift of a car, or a vacation. This doesn't sound excessive to me, but it may depend on your culture.

If none of these apply, and there is no other significant specific concern you are worried about, then accept the gift and be grateful.