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	$221.66	5.839%	$234.6027	$234.60	$234.60	$234.60
Purchase #2	$230.30	12.436%	$258.9401	$258.94	$258.95	$258.90
Purchase #3	$34.48	3.422%	$35.6599	$35.66	$35.65	$35.70
Purchase #4	$188.43	4.351%	$196.6286	$196.63	$196.65	$196.60
Purchase #5	$220.25	13.700%	$250.4243	$250.42	$250.40	$250.40
Purchase #6	$74.79	4.859%	$78.424	$78.42	$78.40	$78.40
Purchase #7	$39.27	9.418%	$42.9684	$42.97	$42.95	$43.00
7 purchase totals =	$1,009.18		$1,097.6480	$1,097.64	$1,097.60	$1,097.60