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	$142.89	10.525%	$157.9292	$157.93	$157.95	$157.90
Purchase #2	$217.27	6.442%	$231.2665	$231.27	$231.25	$231.30
Purchase #3	$155.52	4.757%	$162.9181	$162.92	$162.90	$162.90
Purchase #4	$109.50	4.227%	$114.1286	$114.13	$114.15	$114.10
Purchase #5	$31.60	13.855%	$35.9782	$35.98	$36.00	$36.00
Purchase #6	$226.88	4.854%	$237.8928	$237.89	$237.90	$237.90
Purchase #7	$89.88	13.215%	$101.7576	$101.76	$101.75	$101.80
7 purchase totals =	$973.54		$1,041.8710	$1,041.88	$1,041.90	$1,041.90