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	$130.38	11.235%	$145.0282	$145.03	$145.05	$145.00
Purchase #2	$90.65	9.123%	$98.92	$98.92	$98.90	$98.90
Purchase #3	$53.64	10.681%	$59.3693	$59.37	$59.35	$59.40
Purchase #4	$194.49	11.372%	$216.6074	$216.61	$216.60	$216.60
Purchase #5	$128.66	4.535%	$134.4947	$134.49	$134.50	$134.50
Purchase #6	$244.56	9.660%	$268.1845	$268.18	$268.20	$268.20
Purchase #7	$138.78	4.478%	$144.9946	$144.99	$145.00	$145.00
7 purchase totals =	$981.16		$1,067.5987	$1,067.59	$1,067.60	$1,067.60