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	$237.49	10.690%	$262.8777	$262.88	$262.90	$262.90
Purchase #2	$134.66	13.393%	$152.695	$152.70	$152.70	$152.70
Purchase #3	$223.57	10.449%	$246.9308	$246.93	$246.95	$246.90
Purchase #4	$54.94	5.308%	$57.8562	$57.86	$57.85	$57.90
Purchase #5	$63.56	5.578%	$67.1054	$67.11	$67.10	$67.10
Purchase #6	$122.30	6.581%	$130.3486	$130.35	$130.35	$130.30
Purchase #7	$119.76	10.121%	$131.8809	$131.88	$131.90	$131.90
7 purchase totals =	$956.28		$1,049.6946	$1,049.71	$1,049.75	$1,049.70