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	$91.26	12.784%	$102.9267	$102.93	$102.95	$102.90
Purchase #2	$207.25	5.403%	$218.4477	$218.45	$218.45	$218.40
Purchase #3	$75.88	9.828%	$83.3375	$83.34	$83.35	$83.30
Purchase #4	$220.27	6.633%	$234.8805	$234.88	$234.90	$234.90
Purchase #5	$176.51	11.387%	$196.6092	$196.61	$196.60	$196.60
Purchase #6	$97.36	4.641%	$101.8785	$101.88	$101.90	$101.90
Purchase #7	$117.51	4.874%	$123.2374	$123.24	$123.25	$123.20
7 purchase totals =	$986.04		$1,061.3175	$1,061.33	$1,061.40	$1,061.20