feat(charge): payloadJson의 amount

- 소수점 아래 불필요한 0을 제거

src/main/kotlin/kr/co/vividnext/sodalive/can/charge/ChargeService.kt

@@ -33,6 +33,7 @@ import org.springframework.retry.annotation.Retryable
 import org.springframework.stereotype.Service
 import org.springframework.transaction.annotation.Transactional
 import java.math.BigDecimal
+import java.math.RoundingMode
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 
@@ -264,7 +265,7 @@ class ChargeService(
         val savedCharge = chargeRepository.save(charge)
 
         val chargeId = savedCharge.id!!
-        val amount = savedCharge.payment!!.price
+        val amount = savedCharge.payment!!.price.setScale(4, RoundingMode.HALF_UP).stripTrailingZeros()
         val reqDate = savedCharge.createdAt!!.format(DateTimeFormatter.ofPattern("yyyyMMddHHmmss"))
         val sign = DigestUtils.sha512Hex(
             String.format(