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	$164.55	6.667%	$175.5205	$175.52	$175.50	$175.50
Purchase #2	$75.74	10.120%	$83.4049	$83.40	$83.40	$83.40
Purchase #3	$192.49	3.171%	$198.5939	$198.59	$198.60	$198.60
Purchase #4	$16.85	3.721%	$17.477	$17.48	$17.50	$17.50
Purchase #5	$156.48	5.370%	$164.883	$164.88	$164.90	$164.90
Purchase #6	$161.92	13.676%	$184.0642	$184.06	$184.05	$184.10
Purchase #7	$244.42	6.786%	$261.0063	$261.01	$261.00	$261.00
7 purchase totals =	$1,012.45		$1,084.9498	$1,084.94	$1,084.95	$1,085.00