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	$153.95	9.436%	$168.4767	$168.48	$168.50	$168.50
Purchase #2	$18.66	4.804%	$19.5564	$19.56	$19.55	$19.60
Purchase #3	$186.93	5.143%	$196.5438	$196.54	$196.55	$196.50
Purchase #4	$222.77	6.122%	$236.408	$236.41	$236.40	$236.40
Purchase #5	$20.44	8.558%	$22.1893	$22.19	$22.20	$22.20
Purchase #6	$242.46	10.653%	$268.2893	$268.29	$268.30	$268.30
Purchase #7	$133.47	13.835%	$151.9356	$151.94	$151.95	$151.90
7 purchase totals =	$978.68		$1,063.3991	$1,063.41	$1,063.45	$1,063.40