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	$174.33	4.175%	$181.6083	$181.61	$181.60	$181.60
Purchase #2	$148.25	3.122%	$152.8784	$152.88	$152.90	$152.90
Purchase #3	$173.92	3.788%	$180.5081	$180.51	$180.50	$180.50
Purchase #4	$68.51	5.108%	$72.0095	$72.01	$72.00	$72.00
Purchase #5	$102.51	11.788%	$114.5939	$114.59	$114.60	$114.60
Purchase #6	$126.45	6.737%	$134.9689	$134.97	$134.95	$135.00
Purchase #7	$245.64	7.850%	$264.9227	$264.92	$264.90	$264.90
7 purchase totals =	$1,039.61		$1,101.4898	$1,101.49	$1,101.45	$1,101.50