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	$126.48	12.167%	$141.8688	$141.87	$141.85	$141.90
Purchase #2	$174.54	12.321%	$196.0451	$196.05	$196.05	$196.00
Purchase #3	$173.81	7.561%	$186.9518	$186.95	$186.95	$187.00
Purchase #4	$41.61	4.808%	$43.6106	$43.61	$43.60	$43.60
Purchase #5	$43.79	8.669%	$47.5862	$47.59	$47.60	$47.60
Purchase #6	$18.60	10.364%	$20.5277	$20.53	$20.55	$20.50
Purchase #7	$120.38	6.873%	$128.6537	$128.65	$128.65	$128.70
7 purchase totals =	$699.21		$765.2439	$765.25	$765.25	$765.30