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	$174.97	11.141%	$194.4634	$194.46	$194.45	$194.50
Purchase #2	$43.59	6.716%	$46.5175	$46.52	$46.50	$46.50
Purchase #3	$81.95	5.638%	$86.5703	$86.57	$86.55	$86.60
Purchase #4	$119.52	6.540%	$127.3366	$127.34	$127.35	$127.30
Purchase #5	$201.35	3.416%	$208.2281	$208.23	$208.25	$208.20
Purchase #6	$118.94	3.621%	$123.2468	$123.25	$123.25	$123.20
Purchase #7	$177.57	6.318%	$188.7889	$188.79	$188.80	$188.80
7 purchase totals =	$917.89		$975.1516	$975.16	$975.15	$975.10