t, Sql Server - rextester

Language: Layout:

create table #Sales
	( SiteName nvarchar(1),
		SaleTime time,
		Amount decimal,
		BusinessDate Date );

insert into #Sales ( SiteName, SaleTime, Amount, BusinessDate )
	values 
	( 'A', '13:22:36', 888, '2017-01-02' ),
	( 'A', '00:00:00', 20, '2017-01-02' ),
	( 'A', '00:00:00', 30, '2017-01-02' ),
	( 'A', '00:45:00', 88, '2017-01-02' ),
	( 'A', '12:46:05', 22, '2017-01-02' ),
	( 'A', '12:59:59', 22, '2017-01-02' ),
	( 'A', '23:59:59', 10, '2017-01-02' );

-- Below is actual query:

with rec as(
		select cast('00:00:00' as time) as dt
		union all
		select DATEADD (mi , 15 , dt)  from rec 
		where
		dt < cast('23:45:00' as time)  
	)
	select rec.dt, t1.summ from rec
	left join 
	(select part, sum(Amount) as summ from (
		select *, case 
			when DATEPART ( mi , SaleTime ) < 15 then concat(SUBSTRING (cast(SaleTime as varchar) ,1 , 2 ), ':00:00')
			when DATEPART ( mi , SaleTime ) between 15 and 29 then concat(SUBSTRING (cast(SaleTime as varchar) ,1 , 2 ), ':15:00') 
			when DATEPART ( mi , SaleTime ) between 30 and 44 then concat(SUBSTRING (cast(SaleTime as varchar) ,1 , 2 ), ':30:00') 
			when DATEPART ( mi , SaleTime ) > 44 then concat(SUBSTRING (cast(SaleTime as varchar) ,1 , 2 ), ':45:00') 
			end as part
		from #Sales
		where BusinessDate = '2017-01-02'
	) t
	group by part) t1
	on rec.dt = t1.part
	order by rec.dt

View schema
Execution time: 0,03 sec, rows selected: 96, rows affected: 7, absolute service time: 0,19 sec

	dt	summ
1	00:00:00	50
2	00:15:00	NULL
3	00:30:00	NULL
4	00:45:00	88
5	01:00:00	NULL
6	01:15:00	NULL
7	01:30:00	NULL
8	01:45:00	NULL
9	02:00:00	NULL
10	02:15:00	NULL
11	02:30:00	NULL
12	02:45:00	NULL
13	03:00:00	NULL
14	03:15:00	NULL
15	03:30:00	NULL
16	03:45:00	NULL
17	04:00:00	NULL
18	04:15:00	NULL
19	04:30:00	NULL
20	04:45:00	NULL
21	05:00:00	NULL
22	05:15:00	NULL
23	05:30:00	NULL
24	05:45:00	NULL
25	06:00:00	NULL
26	06:15:00	NULL
27	06:30:00	NULL
28	06:45:00	NULL
29	07:00:00	NULL
30	07:15:00	NULL
31	07:30:00	NULL
32	07:45:00	NULL
33	08:00:00	NULL
34	08:15:00	NULL
35	08:30:00	NULL
36	08:45:00	NULL
37	09:00:00	NULL
38	09:15:00	NULL
39	09:30:00	NULL
40	09:45:00	NULL
41	10:00:00	NULL
42	10:15:00	NULL
43	10:30:00	NULL
44	10:45:00	NULL
45	11:00:00	NULL
46	11:15:00	NULL
47	11:30:00	NULL
48	11:45:00	NULL
49	12:00:00	NULL
50	12:15:00	NULL
51	12:30:00	NULL
52	12:45:00	44
53	13:00:00	NULL
54	13:15:00	888
55	13:30:00	NULL
56	13:45:00	NULL
57	14:00:00	NULL
58	14:15:00	NULL
59	14:30:00	NULL
60	14:45:00	NULL
61	15:00:00	NULL
62	15:15:00	NULL
63	15:30:00	NULL
64	15:45:00	NULL
65	16:00:00	NULL
66	16:15:00	NULL
67	16:30:00	NULL
68	16:45:00	NULL
69	17:00:00	NULL
70	17:15:00	NULL
71	17:30:00	NULL
72	17:45:00	NULL
73	18:00:00	NULL
74	18:15:00	NULL
75	18:30:00	NULL
76	18:45:00	NULL
77	19:00:00	NULL
78	19:15:00	NULL
79	19:30:00	NULL
80	19:45:00	NULL
81	20:00:00	NULL
82	20:15:00	NULL
83	20:30:00	NULL
84	20:45:00	NULL
85	21:00:00	NULL
86	21:15:00	NULL
87	21:30:00	NULL
88	21:45:00	NULL
89	22:00:00	NULL
90	22:15:00	NULL
91	22:30:00	NULL
92	22:45:00	NULL
93	23:00:00	NULL
94	23:15:00	NULL
95	23:30:00	NULL
96	23:45:00	10