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	$168.56	3.650%	$174.7124	$174.71	$174.70	$174.70
Purchase #2	$54.29	9.663%	$59.536	$59.54	$59.55	$59.50
Purchase #3	$96.43	9.664%	$105.749	$105.75	$105.75	$105.70
Purchase #4	$179.86	3.701%	$186.5166	$186.52	$186.50	$186.50
Purchase #5	$97.80	6.359%	$104.0191	$104.02	$104.00	$104.00
Purchase #6	$207.58	4.857%	$217.6622	$217.66	$217.65	$217.70
Purchase #7	$74.40	8.275%	$80.5566	$80.56	$80.55	$80.60
7 purchase totals =	$878.92		$928.7519	$928.76	$928.70	$928.70