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	$196.49	9.237%	$214.6398	$214.64	$214.65	$214.60
Purchase #2	$197.99	5.517%	$208.9131	$208.91	$208.90	$208.90
Purchase #3	$74.90	5.241%	$78.8255	$78.83	$78.85	$78.80
Purchase #4	$228.78	5.137%	$240.5324	$240.53	$240.55	$240.50
Purchase #5	$102.35	3.255%	$105.6815	$105.68	$105.70	$105.70
Purchase #6	$245.55	9.535%	$268.9632	$268.96	$268.95	$269.00
Purchase #7	$60.61	11.822%	$67.7753	$67.78	$67.80	$67.80
7 purchase totals =	$1,106.67		$1,185.3308	$1,185.33	$1,185.40	$1,185.30