You can It's not advised for lower tiers. Mods do tend to say round to the nearest 10 Keys (918 rounds to 920 not 915 also) but a resuggestion on this hardly changes the mid-point. Upvoted

Rounding cash/mp sales is fine. The reason for rounding, aside from aestetic purposes, is that in occurring sales, there's typically an uncertainty involved. In cash/mp sales, that uncertainty lies within fees and fluctuating key-cash conversion values (and in regular paypal sales only the latter). The "best not to round pure sales" really only goes for pure (since if something sold for 53 keys, there's no uncertainty. 53 keys = 53 keys, so rounding that to 55 is kinda weird, especially if it's a flat value suggestion), and even there - on high tiers that have a range anyway - it often doesn't matter that much, so you're good here.