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	$177.98	10.862%	$197.3122	$197.31	$197.30	$197.30
Purchase #2	$81.33	9.757%	$89.2654	$89.27	$89.25	$89.30
Purchase #3	$100.57	5.175%	$105.7745	$105.77	$105.75	$105.80
Purchase #4	$240.73	5.226%	$253.3105	$253.31	$253.30	$253.30
Purchase #5	$213.71	13.682%	$242.9498	$242.95	$242.95	$242.90
Purchase #6	$99.33	8.291%	$107.5655	$107.57	$107.55	$107.60
Purchase #7	$59.94	4.742%	$62.7824	$62.78	$62.80	$62.80
7 purchase totals =	$973.59		$1,058.9603	$1,058.96	$1,058.90	$1,059.00