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	$119.50	7.638%	$128.6274	$128.63	$128.65	$128.60
Purchase #2	$30.52	9.241%	$33.3404	$33.34	$33.35	$33.30
Purchase #3	$97.66	13.699%	$111.0384	$111.04	$111.05	$111.00
Purchase #4	$74.93	3.171%	$77.306	$77.31	$77.30	$77.30
Purchase #5	$180.83	12.162%	$202.8225	$202.82	$202.80	$202.80
Purchase #6	$248.28	8.642%	$269.7364	$269.74	$269.75	$269.70
Purchase #7	$213.93	11.443%	$238.41	$238.41	$238.40	$238.40
7 purchase totals =	$965.65		$1,061.2811	$1,061.29	$1,061.30	$1,061.10