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	$191.94	11.752%	$214.4968	$214.50	$214.50	$214.50
Purchase #2	$175.46	4.838%	$183.9488	$183.95	$183.95	$183.90
Purchase #3	$95.48	3.357%	$98.6853	$98.69	$98.70	$98.70
Purchase #4	$157.41	11.121%	$174.9156	$174.92	$174.90	$174.90
Purchase #5	$250.71	3.538%	$259.5801	$259.58	$259.60	$259.60
Purchase #6	$170.78	8.628%	$185.5149	$185.51	$185.50	$185.50
Purchase #7	$46.27	8.780%	$50.3325	$50.33	$50.35	$50.30
7 purchase totals =	$1,088.05		$1,167.4740	$1,167.48	$1,167.50	$1,167.40