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	$79.69	8.452%	$86.4254	$86.43	$86.45	$86.40
Purchase #2	$151.92	9.686%	$166.635	$166.64	$166.65	$166.60
Purchase #3	$209.27	6.801%	$223.5025	$223.50	$223.50	$223.50
Purchase #4	$162.40	12.592%	$182.8494	$182.85	$182.85	$182.80
Purchase #5	$190.25	12.390%	$213.822	$213.82	$213.80	$213.80
Purchase #6	$167.82	5.245%	$176.6222	$176.62	$176.60	$176.60
Purchase #7	$187.37	5.718%	$198.0838	$198.08	$198.10	$198.10
7 purchase totals =	$1,148.72		$1,247.9403	$1,247.94	$1,247.95	$1,247.80