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	$218.82	11.675%	$244.3672	$244.37	$244.35	$244.40
Purchase #2	$244.33	4.454%	$255.2125	$255.21	$255.20	$255.20
Purchase #3	$42.25	9.354%	$46.2021	$46.20	$46.20	$46.20
Purchase #4	$136.74	5.184%	$143.8286	$143.83	$143.85	$143.80
Purchase #5	$147.27	13.727%	$167.4858	$167.49	$167.50	$167.50
Purchase #6	$196.35	3.785%	$203.7818	$203.78	$203.80	$203.80
Purchase #7	$99.83	5.785%	$105.6052	$105.61	$105.60	$105.60
7 purchase totals =	$1,085.59		$1,166.4832	$1,166.49	$1,166.50	$1,166.50