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	$212.89	4.755%	$223.0129	$223.01	$223.00	$223.00
Purchase #2	$238.56	10.602%	$263.8521	$263.85	$263.85	$263.90
Purchase #3	$157.93	5.747%	$167.0062	$167.01	$167.00	$167.00
Purchase #4	$125.51	4.840%	$131.5847	$131.58	$131.60	$131.60
Purchase #5	$163.97	9.825%	$180.0801	$180.08	$180.10	$180.10
Purchase #6	$115.63	13.328%	$131.0412	$131.04	$131.05	$131.00
Purchase #7	$96.89	7.854%	$104.4997	$104.50	$104.50	$104.50
7 purchase totals =	$1,111.38		$1,201.0769	$1,201.07	$1,201.10	$1,201.10