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	$243.98	9.850%	$268.012	$268.01	$268.00	$268.00
Purchase #2	$141.25	7.142%	$151.3381	$151.34	$151.35	$151.30
Purchase #3	$76.61	9.116%	$83.5938	$83.59	$83.60	$83.60
Purchase #4	$212.64	7.483%	$228.5519	$228.55	$228.55	$228.60
Purchase #5	$166.63	3.648%	$172.7087	$172.71	$172.70	$172.70
Purchase #6	$80.92	7.274%	$86.8061	$86.81	$86.80	$86.80
Purchase #7	$41.89	11.356%	$46.647	$46.65	$46.65	$46.60
7 purchase totals =	$963.92		$1,037.6576	$1,037.66	$1,037.65	$1,037.60