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	$149.94	9.579%	$164.3028	$164.30	$164.30	$164.30
Purchase #2	$168.62	3.390%	$174.3362	$174.34	$174.35	$174.30
Purchase #3	$165.40	4.488%	$172.8232	$172.82	$172.80	$172.80
Purchase #4	$217.92	4.831%	$228.4477	$228.45	$228.45	$228.40
Purchase #5	$41.53	11.676%	$46.379	$46.38	$46.40	$46.40
Purchase #6	$187.46	13.250%	$212.2985	$212.30	$212.30	$212.30
Purchase #7	$35.74	9.175%	$39.0191	$39.02	$39.00	$39.00
7 purchase totals =	$966.61		$1,037.6065	$1,037.61	$1,037.60	$1,037.50