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	$83.48	13.832%	$95.027	$95.03	$95.05	$95.00
Purchase #2	$48.73	3.237%	$50.3074	$50.31	$50.30	$50.30
Purchase #3	$236.89	11.273%	$263.5946	$263.59	$263.60	$263.60
Purchase #4	$66.74	9.262%	$72.9215	$72.92	$72.90	$72.90
Purchase #5	$105.49	7.264%	$113.1528	$113.15	$113.15	$113.20
Purchase #6	$238.92	6.225%	$253.7928	$253.79	$253.80	$253.80
Purchase #7	$151.73	13.257%	$171.8448	$171.84	$171.85	$171.80
7 purchase totals =	$931.98		$1,020.6409	$1,020.63	$1,020.65	$1,020.60