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	$190.97	8.571%	$207.338	$207.34	$207.35	$207.30
Purchase #2	$27.30	8.201%	$29.5389	$29.54	$29.55	$29.50
Purchase #3	$113.97	11.518%	$127.0971	$127.10	$127.10	$127.10
Purchase #4	$152.59	3.795%	$158.3808	$158.38	$158.40	$158.40
Purchase #5	$174.83	12.345%	$196.4128	$196.41	$196.40	$196.40
Purchase #6	$38.58	11.544%	$43.0337	$43.03	$43.05	$43.00
Purchase #7	$75.72	13.801%	$86.1701	$86.17	$86.15	$86.20
7 purchase totals =	$773.96		$847.9714	$847.97	$848.00	$847.90