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	$204.42	7.293%	$219.3284	$219.33	$219.35	$219.30
Purchase #2	$168.83	3.550%	$174.8235	$174.82	$174.80	$174.80
Purchase #3	$177.29	5.371%	$186.8122	$186.81	$186.80	$186.80
Purchase #4	$170.71	9.788%	$187.4191	$187.42	$187.40	$187.40
Purchase #5	$248.79	5.164%	$261.6375	$261.64	$261.65	$261.60
Purchase #6	$244.26	4.585%	$255.4593	$255.46	$255.45	$255.50
Purchase #7	$174.52	12.441%	$196.232	$196.23	$196.25	$196.20
7 purchase totals =	$1,388.82		$1,481.7120	$1,481.71	$1,481.70	$1,481.60