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	$119.95	9.652%	$131.5276	$131.53	$131.55	$131.50
Purchase #2	$96.27	4.665%	$100.761	$100.76	$100.75	$100.80
Purchase #3	$193.62	3.572%	$200.5361	$200.54	$200.55	$200.50
Purchase #4	$214.72	9.460%	$235.0325	$235.03	$235.05	$235.00
Purchase #5	$101.62	3.801%	$105.4826	$105.48	$105.50	$105.50
Purchase #6	$6.33	7.415%	$6.7994	$6.80	$6.80	$6.80
Purchase #7	$228.57	12.135%	$256.307	$256.31	$256.30	$256.30
7 purchase totals =	$961.08		$1,036.4462	$1,036.45	$1,036.50	$1,036.40