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	$176.49	11.127%	$196.128	$196.13	$196.15	$196.10
Purchase #2	$186.58	5.413%	$196.6796	$196.68	$196.70	$196.70
Purchase #3	$159.70	9.865%	$175.4544	$175.45	$175.45	$175.50
Purchase #4	$102.57	10.749%	$113.5952	$113.60	$113.60	$113.60
Purchase #5	$112.94	12.758%	$127.3489	$127.35	$127.35	$127.30
Purchase #6	$36.90	12.850%	$41.6417	$41.64	$41.65	$41.60
Purchase #7	$79.86	5.690%	$84.404	$84.40	$84.40	$84.40
7 purchase totals =	$855.04		$935.2518	$935.25	$935.30	$935.20