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	$84.98	12.442%	$95.5532	$95.55	$95.55	$95.60
Purchase #2	$38.81	9.746%	$42.5924	$42.59	$42.60	$42.60
Purchase #3	$71.56	7.153%	$76.6787	$76.68	$76.70	$76.70
Purchase #4	$35.69	7.279%	$38.2879	$38.29	$38.30	$38.30
Purchase #5	$32.39	7.752%	$34.9009	$34.90	$34.90	$34.90
Purchase #6	$78.31	5.204%	$82.3853	$82.39	$82.40	$82.40
Purchase #7	$59.65	3.747%	$61.8851	$61.89	$61.90	$61.90
7 purchase totals =	$401.39		$432.2835	$432.29	$432.35	$432.40