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	$40.94	8.140%	$44.2725	$44.27	$44.25	$44.30
Purchase #2	$84.76	11.538%	$94.5396	$94.54	$94.55	$94.50
Purchase #3	$247.37	3.576%	$256.216	$256.22	$256.20	$256.20
Purchase #4	$110.53	11.597%	$123.3482	$123.35	$123.35	$123.30
Purchase #5	$202.57	11.292%	$225.4442	$225.44	$225.45	$225.40
Purchase #6	$131.47	3.528%	$136.1083	$136.11	$136.10	$136.10
Purchase #7	$196.32	4.146%	$204.4594	$204.46	$204.45	$204.50
7 purchase totals =	$1,013.96		$1,084.3882	$1,084.39	$1,084.35	$1,084.30