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	$219.50	7.599%	$236.1798	$236.18	$236.20	$236.20
Purchase #2	$64.80	10.360%	$71.5133	$71.51	$71.50	$71.50
Purchase #3	$160.33	7.661%	$172.6129	$172.61	$172.60	$172.60
Purchase #4	$101.25	6.847%	$108.1826	$108.18	$108.20	$108.20
Purchase #5	$159.48	8.127%	$172.4409	$172.44	$172.45	$172.40
Purchase #6	$87.58	5.570%	$92.4582	$92.46	$92.45	$92.50
Purchase #7	$174.28	3.767%	$180.8451	$180.85	$180.85	$180.80
7 purchase totals =	$967.22		$1,034.2328	$1,034.23	$1,034.25	$1,034.20