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	$180.94	13.379%	$205.148	$205.15	$205.15	$205.10
Purchase #2	$77.60	3.798%	$80.5472	$80.55	$80.55	$80.50
Purchase #3	$42.30	3.388%	$43.7331	$43.73	$43.75	$43.70
Purchase #4	$226.92	3.368%	$234.5627	$234.56	$234.55	$234.60
Purchase #5	$54.43	12.180%	$61.0596	$61.06	$61.05	$61.10
Purchase #6	$152.73	4.467%	$159.5524	$159.55	$159.55	$159.60
Purchase #7	$70.42	9.205%	$76.9022	$76.90	$76.90	$76.90
7 purchase totals =	$805.34		$861.5052	$861.50	$861.50	$861.50