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	$188.50	13.468%	$213.8872	$213.89	$213.90	$213.90
Purchase #2	$193.83	13.308%	$219.6249	$219.62	$219.60	$219.60
Purchase #3	$48.69	4.442%	$50.8528	$50.85	$50.85	$50.90
Purchase #4	$12.89	9.798%	$14.153	$14.15	$14.15	$14.20
Purchase #5	$188.77	11.556%	$210.5843	$210.58	$210.60	$210.60
Purchase #6	$151.44	13.118%	$171.3059	$171.31	$171.30	$171.30
Purchase #7	$5.47	5.508%	$5.7713	$5.77	$5.75	$5.80
7 purchase totals =	$789.59		$886.1794	$886.17	$886.15	$886.30