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	$59.43	4.519%	$62.1156	$62.12	$62.10	$62.10
Purchase #2	$187.58	3.697%	$194.5148	$194.51	$194.50	$194.50
Purchase #3	$65.27	3.431%	$67.5094	$67.51	$67.50	$67.50
Purchase #4	$124.67	3.154%	$128.6021	$128.60	$128.60	$128.60
Purchase #5	$186.98	8.573%	$203.0098	$203.01	$203.00	$203.00
Purchase #6	$160.25	12.264%	$179.9031	$179.90	$179.90	$179.90
Purchase #7	$250.67	3.573%	$259.6264	$259.63	$259.65	$259.60
7 purchase totals =	$1,034.85		$1,095.2812	$1,095.28	$1,095.25	$1,095.20