Shall we continue to sin after salvation?

1What shall we say, then? Shall we go on sinning so that grace may increase? Romans 6:1
15What then? Shall we sin because we are not under law but under grace? 6:15
Nothing is free, even the grace of God. Jesus paid the price for our sins.
Just like shaving, sometimes when you cut yourself, if there is a lotion which can heal quickly, does that mean that you can continue to cut yourself repeatably? The lotion does not come cheap also.
We should let our bodies be the slaves of righteousness, instead of letting our bodies to become the slaves of sins. We are dead so long as sins are concerned. We are alive to the righteousness of God.