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	$166.36	9.330%	$181.8814	$181.88	$181.90	$181.90
Purchase #2	$71.52	6.409%	$76.1037	$76.10	$76.10	$76.10
Purchase #3	$40.25	10.170%	$44.3434	$44.34	$44.35	$44.30
Purchase #4	$249.54	8.331%	$270.3292	$270.33	$270.35	$270.30
Purchase #5	$190.41	5.146%	$200.2085	$200.21	$200.20	$200.20
Purchase #6	$246.66	3.513%	$255.3252	$255.33	$255.35	$255.30
Purchase #7	$63.35	6.776%	$67.6426	$67.64	$67.65	$67.60
7 purchase totals =	$1,028.09		$1,095.8340	$1,095.83	$1,095.90	$1,095.70