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	$179.82	9.222%	$196.403	$196.40	$196.40	$196.40
Purchase #2	$203.73	9.337%	$222.7523	$222.75	$222.75	$222.80
Purchase #3	$98.38	4.628%	$102.933	$102.93	$102.95	$102.90
Purchase #4	$120.92	6.568%	$128.862	$128.86	$128.85	$128.90
Purchase #5	$29.80	7.108%	$31.9182	$31.92	$31.90	$31.90
Purchase #6	$86.37	8.411%	$93.6346	$93.63	$93.65	$93.60
Purchase #7	$244.37	6.326%	$259.8288	$259.83	$259.85	$259.80
7 purchase totals =	$963.39		$1,036.3319	$1,036.32	$1,036.35	$1,036.30