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	$59.32	4.437%	$61.952	$61.95	$61.95	$62.00
Purchase #2	$27.48	5.421%	$28.9697	$28.97	$28.95	$29.00
Purchase #3	$18.74	10.850%	$20.7733	$20.77	$20.75	$20.80
Purchase #4	$82.40	9.676%	$90.373	$90.37	$90.35	$90.40
Purchase #5	$51.38	9.337%	$56.1774	$56.18	$56.20	$56.20
Purchase #6	$101.47	12.674%	$114.3303	$114.33	$114.35	$114.30
Purchase #7	$98.67	3.338%	$101.9636	$101.96	$101.95	$102.00
7 purchase totals =	$439.46		$474.5393	$474.53	$474.50	$474.70