Dice roll simulator (updated) created using Python 3.5 and PyQt5
Nice code, so only some comments.

ONE_DIE_PARMS = 1427, 30, 162, 201
TWO_DICE_PARMS = 1265, 30, 324, 201


Never used, typo in the first of them.

In contrast, there are other magic numbers in your code which deserve names for them.



DICE = ('dice_1.png', 'dice_2.png', 'dice_3.png', 'dice_4.png', 'dice_5',
        'dice_6.png')


may become

DICE_TEMPLATE = 'dice_{}.png'
DICE = [DICE_TEMPLATE.format(i) for i in range(1, 7)]


(BTW. it's common to use plural for names of collections - DICES)



geo2 = geo[19:len(geo) - 1]


may become

geo2 = geo[19:-1]


as negative numbers in slices mean "from the end".