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	$73.60	3.278%	$76.0126	$76.01	$76.00	$76.00
Purchase #2	$32.87	3.121%	$33.8959	$33.90	$33.90	$33.90
Purchase #3	$137.58	12.633%	$154.9605	$154.96	$154.95	$155.00
Purchase #4	$145.66	6.834%	$155.6144	$155.61	$155.60	$155.60
Purchase #5	$81.70	11.168%	$90.8243	$90.82	$90.80	$90.80
Purchase #6	$210.46	3.745%	$218.3417	$218.34	$218.35	$218.30
Purchase #7	$29.44	10.502%	$32.5318	$32.53	$32.55	$32.50
7 purchase totals =	$711.31		$762.1812	$762.17	$762.15	$762.10