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	$215.29	13.777%	$244.9505	$244.95	$244.95	$245.00
Purchase #2	$25.61	5.791%	$27.0931	$27.09	$27.10	$27.10
Purchase #3	$224.53	10.403%	$247.8879	$247.89	$247.90	$247.90
Purchase #4	$137.36	11.207%	$152.7539	$152.75	$152.75	$152.80
Purchase #5	$112.73	4.507%	$117.8107	$117.81	$117.80	$117.80
Purchase #6	$96.43	13.569%	$109.5146	$109.51	$109.50	$109.50
Purchase #7	$143.90	11.508%	$160.46	$160.46	$160.45	$160.50
7 purchase totals =	$955.85		$1,060.4707	$1,060.46	$1,060.45	$1,060.60