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	$54.92	8.633%	$59.6612	$59.66	$59.65	$59.70
Purchase #2	$176.44	12.363%	$198.2533	$198.25	$198.25	$198.30
Purchase #3	$113.80	11.855%	$127.291	$127.29	$127.30	$127.30
Purchase #4	$215.76	11.656%	$240.909	$240.91	$240.90	$240.90
Purchase #5	$66.60	9.389%	$72.8531	$72.85	$72.85	$72.90
Purchase #6	$159.74	4.842%	$167.4746	$167.47	$167.45	$167.50
Purchase #7	$62.60	5.661%	$66.1438	$66.14	$66.15	$66.10
7 purchase totals =	$849.86		$932.5860	$932.57	$932.55	$932.70