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	$141.48	7.565%	$152.183	$152.18	$152.20	$152.20
Purchase #2	$190.92	3.765%	$198.1081	$198.11	$198.10	$198.10
Purchase #3	$248.75	3.290%	$256.9339	$256.93	$256.95	$256.90
Purchase #4	$154.30	8.630%	$167.6161	$167.62	$167.60	$167.60
Purchase #5	$209.29	8.642%	$227.3768	$227.38	$227.40	$227.40
Purchase #6	$117.36	5.177%	$123.4357	$123.44	$123.45	$123.40
Purchase #7	$210.76	5.722%	$222.8197	$222.82	$222.80	$222.80
7 purchase totals =	$1,272.86		$1,348.4733	$1,348.48	$1,348.50	$1,348.40