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	$194.58	10.260%	$214.5439	$214.54	$214.55	$214.50
Purchase #2	$94.74	4.837%	$99.3226	$99.32	$99.30	$99.30
Purchase #3	$203.31	12.789%	$229.3113	$229.31	$229.30	$229.30
Purchase #4	$113.58	5.259%	$119.5532	$119.55	$119.55	$119.60
Purchase #5	$116.54	9.532%	$127.6486	$127.65	$127.65	$127.60
Purchase #6	$181.61	8.212%	$196.5238	$196.52	$196.50	$196.50
Purchase #7	$244.77	7.197%	$262.3861	$262.39	$262.40	$262.40
7 purchase totals =	$1,149.13		$1,249.2895	$1,249.28	$1,249.25	$1,249.20