Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$192.62	6.857%	$205.828	$205.83	$205.85	$205.80
Purchase #2	$64.96	9.178%	$70.922	$70.92	$70.90	$70.90
Purchase #3	$40.88	12.279%	$45.8997	$45.90	$45.90	$45.90
Purchase #4	$25.97	5.367%	$27.3638	$27.36	$27.35	$27.40
Purchase #5	$101.51	10.269%	$111.9341	$111.93	$111.95	$111.90
Purchase #6	$117.59	8.307%	$127.3582	$127.36	$127.35	$127.40
Purchase #7	$160.43	11.486%	$178.857	$178.86	$178.85	$178.90
7 purchase totals =	$703.96		$768.1628	$768.16	$768.15	$768.20