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	$161.39	9.447%	$176.6365	$176.64	$176.65	$176.60
Purchase #2	$250.98	4.296%	$261.7621	$261.76	$261.75	$261.80
Purchase #3	$111.56	6.594%	$118.9163	$118.92	$118.90	$118.90
Purchase #4	$16.40	13.640%	$18.637	$18.64	$18.65	$18.60
Purchase #5	$234.43	5.792%	$248.0082	$248.01	$248.00	$248.00
Purchase #6	$92.29	6.193%	$98.0055	$98.01	$98.00	$98.00
Purchase #7	$200.61	12.314%	$225.3131	$225.31	$225.30	$225.30
7 purchase totals =	$1,067.66		$1,147.2787	$1,147.29	$1,147.25	$1,147.20