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	$131.88	11.554%	$147.1174	$147.12	$147.10	$147.10
Purchase #2	$78.68	13.673%	$89.4379	$89.44	$89.45	$89.40
Purchase #3	$118.31	6.284%	$125.7446	$125.74	$125.75	$125.70
Purchase #4	$179.39	10.836%	$198.8287	$198.83	$198.85	$198.80
Purchase #5	$77.71	10.489%	$85.861	$85.86	$85.85	$85.90
Purchase #6	$197.66	6.809%	$211.1187	$211.12	$211.10	$211.10
Purchase #7	$153.87	8.856%	$167.4967	$167.50	$167.50	$167.50
7 purchase totals =	$937.50		$1,025.6050	$1,025.61	$1,025.60	$1,025.50