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	$119.82	3.198%	$123.6518	$123.65	$123.65	$123.70
Purchase #2	$169.48	5.851%	$179.3963	$179.40	$179.40	$179.40
Purchase #3	$221.50	11.630%	$247.2605	$247.26	$247.25	$247.30
Purchase #4	$189.33	12.246%	$212.5154	$212.52	$212.50	$212.50
Purchase #5	$173.52	13.359%	$196.7005	$196.70	$196.70	$196.70
Purchase #6	$207.83	13.334%	$235.5421	$235.54	$235.55	$235.50
Purchase #7	$29.47	6.757%	$31.4613	$31.46	$31.45	$31.50
7 purchase totals =	$1,110.95		$1,226.5279	$1,226.53	$1,226.50	$1,226.60