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	$91.66	11.199%	$101.925	$101.93	$101.95	$101.90
Purchase #2	$76.87	7.663%	$82.7605	$82.76	$82.75	$82.80
Purchase #3	$190.56	11.292%	$212.078	$212.08	$212.10	$212.10
Purchase #4	$51.95	3.418%	$53.7257	$53.73	$53.75	$53.70
Purchase #5	$71.72	7.127%	$76.8315	$76.83	$76.85	$76.80
Purchase #6	$61.91	7.528%	$66.5706	$66.57	$66.55	$66.60
Purchase #7	$117.74	11.270%	$131.0093	$131.01	$131.00	$131.00
7 purchase totals =	$662.41		$724.9006	$724.91	$724.95	$724.90