fix gas fee calcuation error (#798)

Co-authored-by: Daniel Choi <13338103+araskachoi@users.noreply.github.com>

CHANGELOG.md

@@ -44,6 +44,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* (evm) [\#799](https://github.com/cosmos/ethermint/issues/799) Fix wrong precision in calculation of gas fee.
 * (evm) [\#760](https://github.com/cosmos/ethermint/issues/760) Fix Failed to call function EstimateGas.
 * (evm) [\#767](https://github.com/cosmos/ethermint/issues/767) Fix error of timeout when using Truffle to deploy contract.
 * (evm) [\#751](https://github.com/cosmos/ethermint/issues/751) Fix misused method to calculate block hash in evm related function.

app/ante/eth.go

@@ -99,7 +99,7 @@ func (emfd EthMempoolFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simula
 	evmDenom := emfd.evmKeeper.GetParams(ctx).EvmDenom
 
 	// fee = gas price * gas limit
-	fee := sdk.NewDecCoin(evmDenom, sdk.NewIntFromBigInt(msgEthTx.Fee()))
+	fee := sdk.NewDecCoinFromDec(evmDenom, sdk.NewDecFromBigIntWithPrec(msgEthTx.Fee(), sdk.Precision))
 
 	minGasPrices := ctx.MinGasPrices()
 	minFees := minGasPrices.AmountOf(evmDenom).MulInt64(int64(msgEthTx.Data.GasLimit))