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	$62.26	8.226%	$67.3815	$67.38	$67.40	$67.40
Purchase #2	$193.81	13.774%	$220.5054	$220.51	$220.50	$220.50
Purchase #3	$228.99	7.551%	$246.281	$246.28	$246.30	$246.30
Purchase #4	$156.31	7.622%	$168.2239	$168.22	$168.20	$168.20
Purchase #5	$198.39	3.537%	$205.4071	$205.41	$205.40	$205.40
Purchase #6	$89.59	11.521%	$99.9117	$99.91	$99.90	$99.90
Purchase #7	$42.31	12.334%	$47.5285	$47.53	$47.55	$47.50
7 purchase totals =	$971.66		$1,055.2391	$1,055.24	$1,055.25	$1,055.20