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	$222.89	9.161%	$243.309	$243.31	$243.30	$243.30
Purchase #2	$78.38	6.669%	$83.6072	$83.61	$83.60	$83.60
Purchase #3	$131.95	9.365%	$144.3071	$144.31	$144.30	$144.30
Purchase #4	$217.37	4.709%	$227.606	$227.61	$227.60	$227.60
Purchase #5	$147.92	12.670%	$166.6615	$166.66	$166.65	$166.70
Purchase #6	$125.76	13.348%	$142.5464	$142.55	$142.55	$142.50
Purchase #7	$150.89	7.400%	$162.0559	$162.06	$162.05	$162.10
7 purchase totals =	$1,075.16		$1,170.0931	$1,170.11	$1,170.05	$1,170.10