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	$171.88	3.300%	$177.552	$177.55	$177.55	$177.60
Purchase #2	$7.34	7.119%	$7.8625	$7.86	$7.85	$7.90
Purchase #3	$232.97	12.825%	$262.8484	$262.85	$262.85	$262.80
Purchase #4	$206.81	7.412%	$222.1388	$222.14	$222.15	$222.10
Purchase #5	$58.48	7.651%	$62.9543	$62.95	$62.95	$63.00
Purchase #6	$128.86	13.653%	$146.4533	$146.45	$146.45	$146.50
Purchase #7	$196.71	4.788%	$206.1285	$206.13	$206.15	$206.10
7 purchase totals =	$1,003.05		$1,085.9378	$1,085.93	$1,085.95	$1,086.00