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	$176.94	10.782%	$196.0177	$196.02	$196.00	$196.00
Purchase #2	$16.86	6.315%	$17.9247	$17.92	$17.90	$17.90
Purchase #3	$160.87	12.392%	$180.805	$180.81	$180.80	$180.80
Purchase #4	$127.73	11.396%	$142.2861	$142.29	$142.30	$142.30
Purchase #5	$67.63	6.537%	$72.051	$72.05	$72.05	$72.10
Purchase #6	$187.33	11.576%	$209.0153	$209.02	$209.00	$209.00
Purchase #7	$75.57	13.528%	$85.7931	$85.79	$85.80	$85.80
7 purchase totals =	$812.93		$903.8929	$903.90	$903.85	$903.90