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	$94.96	6.617%	$101.2435	$101.24	$101.25	$101.20
Purchase #2	$105.93	5.706%	$111.9744	$111.97	$111.95	$112.00
Purchase #3	$194.86	4.144%	$202.935	$202.94	$202.95	$202.90
Purchase #4	$198.85	5.268%	$209.3254	$209.33	$209.35	$209.30
Purchase #5	$50.93	8.503%	$55.2606	$55.26	$55.25	$55.30
Purchase #6	$233.31	9.787%	$256.144	$256.14	$256.15	$256.10
Purchase #7	$59.80	12.772%	$67.4377	$67.44	$67.45	$67.40
7 purchase totals =	$938.64		$1,004.3206	$1,004.32	$1,004.35	$1,004.20