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	$247.82	8.114%	$267.9281	$267.93	$267.95	$267.90
Purchase #2	$17.80	13.801%	$20.2566	$20.26	$20.25	$20.30
Purchase #3	$89.64	10.588%	$99.1311	$99.13	$99.15	$99.10
Purchase #4	$237.84	7.761%	$256.2988	$256.30	$256.30	$256.30
Purchase #5	$73.80	11.337%	$82.1667	$82.17	$82.15	$82.20
Purchase #6	$98.86	3.443%	$102.2637	$102.26	$102.25	$102.30
Purchase #7	$128.86	4.558%	$134.7334	$134.73	$134.75	$134.70
7 purchase totals =	$894.62		$962.7784	$962.78	$962.80	$962.80