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	$178.76	9.446%	$195.6457	$195.65	$195.65	$195.60
Purchase #2	$99.73	12.126%	$111.8233	$111.82	$111.80	$111.80
Purchase #3	$140.34	9.659%	$153.8954	$153.90	$153.90	$153.90
Purchase #4	$9.48	11.129%	$10.535	$10.54	$10.55	$10.50
Purchase #5	$186.38	7.340%	$200.0603	$200.06	$200.05	$200.10
Purchase #6	$157.80	10.669%	$174.6357	$174.64	$174.65	$174.60
Purchase #7	$145.45	6.300%	$154.6134	$154.61	$154.60	$154.60
7 purchase totals =	$917.94		$1,001.2088	$1,001.22	$1,001.20	$1,001.10