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	$117.28	7.559%	$126.1452	$126.15	$126.15	$126.10
Purchase #2	$120.70	13.288%	$136.7386	$136.74	$136.75	$136.70
Purchase #3	$80.89	3.432%	$83.6661	$83.67	$83.65	$83.70
Purchase #4	$211.53	10.407%	$233.5439	$233.54	$233.55	$233.50
Purchase #5	$89.90	8.588%	$97.6206	$97.62	$97.60	$97.60
Purchase #6	$244.95	3.700%	$254.0132	$254.01	$254.00	$254.00
Purchase #7	$123.64	6.408%	$131.5629	$131.56	$131.55	$131.60
7 purchase totals =	$988.89		$1,063.2905	$1,063.29	$1,063.25	$1,063.20