Code:
sysuse nlsw88,clear
reg married i.collgrad##c.wage
margins collgrad, at(wage== (5 10 15)) post



. margins collgrad, at(wage== (5 10 15)) post

Adjusted predictions    Number    of obs    =      2,246
Model VCE    : OLS

Expression   : Linear prediction, predict()

1._at        : wage            =           5

2._at        : wage            =          10

3._at        : wage            =          15

            
Delta-method
Margin   Std. Err.    t    P>t    [95% Conf. Interval]
            
_at#collgrad
1#not college grad     .6452051   .0123095    52.42    0.000    .6210659    .6693443
1#college grad     .6846007   .0275997    24.80    0.000    .630477    .7387244
2#not college grad     .6331711   .0134103    47.22    0.000    .6068732    .6594691
2#college grad     .6502325    .020849    31.19    0.000    .6093471    .6911179
3#not college grad     .6211372   .0211735    29.34    0.000    .5796154    .6626589
3#college grad     .6158643   .0254564    24.19    0.000    .5659437    .6657849
            




display e(b)[1,2] / e(b)[1,1]
display e(b)[1,4] / e(b)[1,3]
display e(b)[1,6] / e(b)[1,5]




I'm using Stata 16.1.