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	$241.60	8.468%	$262.0587	$262.06	$262.05	$262.10
Purchase #2	$165.72	8.581%	$179.9404	$179.94	$179.95	$179.90
Purchase #3	$31.79	6.520%	$33.8627	$33.86	$33.85	$33.90
Purchase #4	$39.66	11.599%	$44.2602	$44.26	$44.25	$44.30
Purchase #5	$127.62	12.474%	$143.5393	$143.54	$143.55	$143.50
Purchase #6	$90.35	4.558%	$94.4682	$94.47	$94.45	$94.50
Purchase #7	$220.41	8.315%	$238.7371	$238.74	$238.75	$238.70
7 purchase totals =	$917.15		$996.8666	$996.87	$996.85	$996.90