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	$213.37	5.482%	$225.0669	$225.07	$225.05	$225.10
Purchase #2	$196.76	8.278%	$213.0478	$213.05	$213.05	$213.00
Purchase #3	$61.82	4.240%	$64.4412	$64.44	$64.45	$64.40
Purchase #4	$115.50	9.256%	$126.1907	$126.19	$126.20	$126.20
Purchase #5	$100.98	13.814%	$114.9294	$114.93	$114.95	$114.90
Purchase #6	$94.78	11.352%	$105.5394	$105.54	$105.55	$105.50
Purchase #7	$194.38	11.580%	$216.8892	$216.89	$216.90	$216.90
7 purchase totals =	$977.59		$1,066.1046	$1,066.11	$1,066.15	$1,066.00