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	$115.67	9.215%	$126.329	$126.33	$126.35	$126.30
Purchase #2	$52.45	3.123%	$54.088	$54.09	$54.10	$54.10
Purchase #3	$144.54	4.134%	$150.5153	$150.52	$150.50	$150.50
Purchase #4	$243.90	12.164%	$273.568	$273.57	$273.55	$273.60
Purchase #5	$211.66	8.358%	$229.3505	$229.35	$229.35	$229.40
Purchase #6	$163.55	9.492%	$179.0742	$179.07	$179.05	$179.10
Purchase #7	$31.77	4.590%	$33.2282	$33.23	$33.25	$33.20
7 purchase totals =	$963.54		$1,046.1532	$1,046.16	$1,046.15	$1,046.20