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	$208.44	7.116%	$223.2726	$223.27	$223.25	$223.30
Purchase #2	$210.41	3.414%	$217.5934	$217.59	$217.60	$217.60
Purchase #3	$209.78	6.348%	$223.0968	$223.10	$223.10	$223.10
Purchase #4	$21.46	7.761%	$23.1255	$23.13	$23.15	$23.10
Purchase #5	$210.45	3.167%	$217.115	$217.12	$217.10	$217.10
Purchase #6	$146.52	4.160%	$152.6152	$152.62	$152.60	$152.60
Purchase #7	$50.75	5.497%	$53.5397	$53.54	$53.55	$53.50
7 purchase totals =	$1,057.81		$1,110.3582	$1,110.37	$1,110.35	$1,110.30