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	$113.27	5.264%	$119.2325	$119.23	$119.25	$119.20
Purchase #2	$169.26	3.354%	$174.937	$174.94	$174.95	$174.90
Purchase #3	$101.82	7.189%	$109.1398	$109.14	$109.15	$109.10
Purchase #4	$239.52	11.415%	$266.8612	$266.86	$266.85	$266.90
Purchase #5	$84.33	10.119%	$92.8634	$92.86	$92.85	$92.90
Purchase #6	$52.58	10.145%	$57.9142	$57.91	$57.90	$57.90
Purchase #7	$245.91	6.323%	$261.4589	$261.46	$261.45	$261.50
7 purchase totals =	$1,006.69		$1,082.4070	$1,082.40	$1,082.40	$1,082.40