Figureing Half Die Roll Based on Attribute Macros

I am working on my player's character sheets where the number of dice rolled is based on the Current Attribute. Here is an example, an character has a Current Attribute of 18 which creates a roll of 3 1/2d6. Any thoughts?

Does it always round up or only at .5 and above? If it always rounds up ((@{Current Attribute}-4)/5)d6s should work. 15 becomes 11, 11/3=2.2 rounds up to 3. 18 becomes 14, 14/5=2.9 rounds up to 3. 20 becomes 16, 16/5=3.1 rounds up to 4. If it rounds up .5 or higher ((@{Current Attribute}-2)/5)d6s should work. 15 becomes 13, 13/3=2.6 rounds up to 3. 18 becomes 16, 16/5=3.1 rounds down to 3. 20 becomes 18, 18/5=3.3 rounds up to 4. I cant run the software from wort to check though.

No, it need to round to the nearest 0.5d6 (half die six).