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	$82.92	13.535%	$94.1432	$94.14	$94.15	$94.10
Purchase #2	$180.38	8.704%	$196.0803	$196.08	$196.10	$196.10
Purchase #3	$92.66	11.276%	$103.1083	$103.11	$103.10	$103.10
Purchase #4	$174.57	9.689%	$191.4841	$191.48	$191.50	$191.50
Purchase #5	$215.30	6.330%	$228.9285	$228.93	$228.95	$228.90
Purchase #6	$137.85	7.378%	$148.0206	$148.02	$148.00	$148.00
Purchase #7	$201.67	7.493%	$216.7811	$216.78	$216.80	$216.80
7 purchase totals =	$1,085.35		$1,178.5461	$1,178.54	$1,178.60	$1,178.50