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	$115.55	11.254%	$128.554	$128.55	$128.55	$128.60
Purchase #2	$39.80	4.374%	$41.5409	$41.54	$41.55	$41.50
Purchase #3	$183.92	5.787%	$194.5635	$194.56	$194.55	$194.60
Purchase #4	$166.63	11.691%	$186.1107	$186.11	$186.10	$186.10
Purchase #5	$180.25	11.254%	$200.5353	$200.54	$200.55	$200.50
Purchase #6	$78.35	8.314%	$84.864	$84.86	$84.85	$84.90
Purchase #7	$172.87	9.719%	$189.6712	$189.67	$189.65	$189.70
7 purchase totals =	$937.37		$1,025.8396	$1,025.83	$1,025.80	$1,025.90