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	$193.46	10.643%	$214.0499	$214.05	$214.05	$214.00
Purchase #2	$52.54	12.655%	$59.1889	$59.19	$59.20	$59.20
Purchase #3	$97.40	3.331%	$100.6444	$100.64	$100.65	$100.60
Purchase #4	$178.33	6.272%	$189.5149	$189.51	$189.50	$189.50
Purchase #5	$172.29	3.703%	$178.6699	$178.67	$178.65	$178.70
Purchase #6	$90.54	13.356%	$102.6325	$102.63	$102.65	$102.60
Purchase #7	$211.47	5.605%	$223.3229	$223.32	$223.30	$223.30
7 purchase totals =	$996.03		$1,068.0234	$1,068.01	$1,068.00	$1,067.90