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	$179.67	9.125%	$196.0649	$196.06	$196.05	$196.10
Purchase #2	$61.59	6.422%	$65.5453	$65.55	$65.55	$65.50
Purchase #3	$200.88	6.749%	$214.4374	$214.44	$214.45	$214.40
Purchase #4	$158.26	6.665%	$168.808	$168.81	$168.80	$168.80
Purchase #5	$169.51	6.469%	$180.4756	$180.48	$180.50	$180.50
Purchase #6	$250.73	9.122%	$273.6016	$273.60	$273.60	$273.60
Purchase #7	$58.78	11.166%	$65.3434	$65.34	$65.35	$65.30
7 purchase totals =	$1,079.42		$1,164.2762	$1,164.28	$1,164.30	$1,164.20