You can create a command entry

I don't really under stand what the decimal glossary is...

The Decimals glossary contain 11000 abbreviations for decimal expansions from 0.01 to 99.99. They are intended to be included in your working glossaries or merged. The short forms in the Decimals.glo all begin with the letter n followed by the corresponding numbers.

Examples:

n08 = 0.8
n099 = 0.99
n1013 = 10.13
n9993 = 99.93

Can't you make a command in IT that will change the spacing, after the fact

Yes, you can create a command entry to remove the spaces.

For example, if you wanted to type the following decimal entry:
5.05

With automatic spacing on, what you get is:
5. 05

With this example, your command entry could look like this:
{command}{Left}{Left}{Left}{Backspace}{Backspace}{end}_

This command entry tells IT to move to the left 3x's, backspace twice to remove the two spaces, then put the cursor at the end of your entry so you can pick up where you left off. The trailing underscore tells IT to not insert an extra space.

Kind regards,
Kristen