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	$174.34	7.465%	$187.3545	$187.35	$187.35	$187.40
Purchase #2	$32.83	5.792%	$34.7315	$34.73	$34.75	$34.70
Purchase #3	$175.48	12.191%	$196.8728	$196.87	$196.85	$196.90
Purchase #4	$37.65	5.713%	$39.8009	$39.80	$39.80	$39.80
Purchase #5	$187.52	3.867%	$194.7714	$194.77	$194.75	$194.80
Purchase #6	$222.38	4.756%	$232.9564	$232.96	$232.95	$233.00
Purchase #7	$104.59	11.294%	$116.4024	$116.40	$116.40	$116.40
7 purchase totals =	$934.79		$1,002.8899	$1,002.88	$1,002.85	$1,003.00