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	$186.77	5.379%	$196.8164	$196.82	$196.80	$196.80
Purchase #2	$38.37	8.757%	$41.7301	$41.73	$41.75	$41.70
Purchase #3	$142.57	12.780%	$160.7904	$160.79	$160.80	$160.80
Purchase #4	$22.86	5.209%	$24.0508	$24.05	$24.05	$24.10
Purchase #5	$117.33	12.793%	$132.34	$132.34	$132.35	$132.30
Purchase #6	$168.91	13.121%	$191.0727	$191.07	$191.05	$191.10
Purchase #7	$199.33	11.691%	$222.6337	$222.63	$222.65	$222.60
7 purchase totals =	$876.14		$969.4341	$969.43	$969.45	$969.40