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	$174.50	12.870%	$196.9582	$196.96	$196.95	$197.00
Purchase #2	$40.97	10.233%	$45.1625	$45.16	$45.15	$45.20
Purchase #3	$32.54	4.257%	$33.9252	$33.93	$33.95	$33.90
Purchase #4	$186.27	7.618%	$200.46	$200.46	$200.45	$200.50
Purchase #5	$160.94	8.157%	$174.0679	$174.07	$174.05	$174.10
Purchase #6	$45.65	13.366%	$51.7516	$51.75	$51.75	$51.80
Purchase #7	$117.52	5.377%	$123.8391	$123.84	$123.85	$123.80
7 purchase totals =	$758.39		$826.1645	$826.17	$826.15	$826.30