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	$163.41	5.296%	$172.0642	$172.06	$172.05	$172.10
Purchase #2	$86.51	9.223%	$94.4888	$94.49	$94.50	$94.50
Purchase #3	$121.72	9.704%	$133.5317	$133.53	$133.55	$133.50
Purchase #4	$96.54	7.259%	$103.5478	$103.55	$103.55	$103.50
Purchase #5	$205.50	4.389%	$214.5194	$214.52	$214.50	$214.50
Purchase #6	$201.83	13.578%	$229.2345	$229.23	$229.25	$229.20
Purchase #7	$51.93	13.713%	$59.0512	$59.05	$59.05	$59.10
7 purchase totals =	$927.44		$1,006.4376	$1,006.43	$1,006.45	$1,006.40