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	$86.75	6.702%	$92.564	$92.56	$92.55	$92.60
Purchase #2	$150.89	7.390%	$162.0408	$162.04	$162.05	$162.00
Purchase #3	$11.42	4.352%	$11.917	$11.92	$11.90	$11.90
Purchase #4	$187.91	6.577%	$200.2688	$200.27	$200.25	$200.30
Purchase #5	$116.56	12.769%	$131.4435	$131.44	$131.45	$131.40
Purchase #6	$125.35	4.532%	$131.0309	$131.03	$131.05	$131.00
Purchase #7	$207.33	4.458%	$216.5728	$216.57	$216.55	$216.60
7 purchase totals =	$886.21		$945.8378	$945.83	$945.80	$945.80