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	$192.61	9.303%	$210.5285	$210.53	$210.55	$210.50
Purchase #2	$47.85	7.193%	$51.2919	$51.29	$51.30	$51.30
Purchase #3	$240.43	8.625%	$261.1671	$261.17	$261.15	$261.20
Purchase #4	$240.89	13.133%	$272.5261	$272.53	$272.55	$272.50
Purchase #5	$83.83	5.568%	$88.4977	$88.50	$88.50	$88.50
Purchase #6	$64.66	10.327%	$71.3374	$71.34	$71.35	$71.30
Purchase #7	$126.83	10.582%	$140.2512	$140.25	$140.25	$140.30
7 purchase totals =	$997.10		$1,095.5999	$1,095.61	$1,095.65	$1,095.60