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	$233.59	9.108%	$254.8654	$254.87	$254.85	$254.90
Purchase #2	$44.71	5.538%	$47.186	$47.19	$47.20	$47.20
Purchase #3	$222.51	7.528%	$239.2606	$239.26	$239.25	$239.30
Purchase #4	$86.35	9.721%	$94.7441	$94.74	$94.75	$94.70
Purchase #5	$211.34	5.870%	$223.7457	$223.75	$223.75	$223.70
Purchase #6	$78.95	13.378%	$89.5119	$89.51	$89.50	$89.50
Purchase #7	$98.35	5.312%	$103.5744	$103.57	$103.55	$103.60
7 purchase totals =	$975.80		$1,052.8881	$1,052.89	$1,052.85	$1,052.90