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	$179.64	6.747%	$191.7603	$191.76	$191.75	$191.80
Purchase #2	$28.66	13.622%	$32.5641	$32.56	$32.55	$32.60
Purchase #3	$203.32	4.398%	$212.262	$212.26	$212.25	$212.30
Purchase #4	$142.55	5.820%	$150.8464	$150.85	$150.85	$150.80
Purchase #5	$185.92	12.749%	$209.6229	$209.62	$209.60	$209.60
Purchase #6	$161.62	9.144%	$176.3985	$176.40	$176.40	$176.40
Purchase #7	$82.85	10.367%	$91.4391	$91.44	$91.45	$91.40
7 purchase totals =	$984.56		$1,064.8933	$1,064.89	$1,064.85	$1,064.90