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	$196.64	10.770%	$217.8181	$217.82	$217.80	$217.80
Purchase #2	$84.41	8.444%	$91.5376	$91.54	$91.55	$91.50
Purchase #3	$56.48	5.376%	$59.5164	$59.52	$59.50	$59.50
Purchase #4	$177.68	9.647%	$194.8208	$194.82	$194.80	$194.80
Purchase #5	$224.39	6.589%	$239.1751	$239.18	$239.20	$239.20
Purchase #6	$159.88	3.465%	$165.4198	$165.42	$165.40	$165.40
Purchase #7	$82.37	11.276%	$91.658	$91.66	$91.65	$91.70
7 purchase totals =	$981.85		$1,059.9458	$1,059.96	$1,059.90	$1,059.90