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	$196.47	7.592%	$211.386	$211.39	$211.40	$211.40
Purchase #2	$76.49	9.631%	$83.8568	$83.86	$83.85	$83.90
Purchase #3	$93.28	6.531%	$99.3721	$99.37	$99.35	$99.40
Purchase #4	$130.32	6.678%	$139.0228	$139.02	$139.00	$139.00
Purchase #5	$198.97	9.692%	$218.2542	$218.25	$218.25	$218.30
Purchase #6	$105.57	9.288%	$115.3753	$115.38	$115.40	$115.40
Purchase #7	$217.62	6.405%	$231.5586	$231.56	$231.55	$231.60
7 purchase totals =	$1,018.72		$1,098.8258	$1,098.83	$1,098.80	$1,099.00