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	$88.66	7.565%	$95.3671	$95.37	$95.35	$95.40
Purchase #2	$202.33	7.312%	$217.1244	$217.12	$217.10	$217.10
Purchase #3	$113.75	6.217%	$120.8218	$120.82	$120.80	$120.80
Purchase #4	$37.85	13.193%	$42.8436	$42.84	$42.85	$42.80
Purchase #5	$217.86	8.545%	$236.4761	$236.48	$236.50	$236.50
Purchase #6	$163.90	4.400%	$171.1116	$171.11	$171.10	$171.10
Purchase #7	$128.96	10.158%	$142.0598	$142.06	$142.05	$142.10
7 purchase totals =	$953.31		$1,025.8044	$1,025.80	$1,025.75	$1,025.80