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	$179.63	7.526%	$193.149	$193.15	$193.15	$193.10
Purchase #2	$112.77	13.447%	$127.9342	$127.93	$127.95	$127.90
Purchase #3	$30.47	4.119%	$31.7251	$31.73	$31.75	$31.70
Purchase #4	$213.90	4.509%	$223.5448	$223.54	$223.55	$223.50
Purchase #5	$236.83	7.828%	$255.3691	$255.37	$255.35	$255.40
Purchase #6	$186.48	5.503%	$196.742	$196.74	$196.75	$196.70
Purchase #7	$87.96	9.581%	$96.3874	$96.39	$96.40	$96.40
7 purchase totals =	$1,048.04		$1,124.8516	$1,124.85	$1,124.90	$1,124.70