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	$129.59	10.632%	$143.368	$143.37	$143.35	$143.40
Purchase #2	$97.40	3.301%	$100.6152	$100.62	$100.60	$100.60
Purchase #3	$191.45	7.795%	$206.3735	$206.37	$206.35	$206.40
Purchase #4	$122.80	9.763%	$134.789	$134.79	$134.80	$134.80
Purchase #5	$135.94	4.696%	$142.3237	$142.32	$142.30	$142.30
Purchase #6	$138.37	6.571%	$147.4623	$147.46	$147.45	$147.50
Purchase #7	$153.54	11.640%	$171.4121	$171.41	$171.40	$171.40
7 purchase totals =	$969.09		$1,046.3438	$1,046.34	$1,046.25	$1,046.40