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	$206.84	9.181%	$225.83	$225.83	$225.85	$225.80
Purchase #2	$98.41	11.697%	$109.921	$109.92	$109.90	$109.90
Purchase #3	$193.47	7.410%	$207.8061	$207.81	$207.80	$207.80
Purchase #4	$242.66	7.844%	$261.6943	$261.69	$261.70	$261.70
Purchase #5	$39.40	10.342%	$43.4747	$43.47	$43.45	$43.50
Purchase #6	$95.86	3.588%	$99.2995	$99.30	$99.30	$99.30
Purchase #7	$226.69	9.158%	$247.4503	$247.45	$247.45	$247.50
7 purchase totals =	$1,103.33		$1,195.4759	$1,195.47	$1,195.45	$1,195.50