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	$193.68	11.191%	$215.3547	$215.35	$215.35	$215.40
Purchase #2	$124.55	5.712%	$131.6643	$131.66	$131.65	$131.70
Purchase #3	$186.50	5.437%	$196.64	$196.64	$196.65	$196.60
Purchase #4	$82.91	6.855%	$88.5935	$88.59	$88.60	$88.60
Purchase #5	$202.96	9.166%	$221.5633	$221.56	$221.55	$221.60
Purchase #6	$207.82	11.472%	$231.6611	$231.66	$231.65	$231.70
Purchase #7	$132.43	6.803%	$141.4392	$141.44	$141.45	$141.40
7 purchase totals =	$1,130.85		$1,226.9161	$1,226.90	$1,226.90	$1,227.00