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	$62.65	8.421%	$67.9258	$67.93	$67.95	$67.90
Purchase #2	$32.68	3.691%	$33.8862	$33.89	$33.90	$33.90
Purchase #3	$95.43	3.498%	$98.7681	$98.77	$98.75	$98.80
Purchase #4	$64.88	3.462%	$67.1261	$67.13	$67.15	$67.10
Purchase #5	$40.38	7.248%	$43.3067	$43.31	$43.30	$43.30
Purchase #6	$188.33	5.275%	$198.2644	$198.26	$198.25	$198.30
Purchase #7	$18.85	5.615%	$19.9084	$19.91	$19.90	$19.90
7 purchase totals =	$503.20		$529.1857	$529.20	$529.20	$529.20