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	$191.77	3.482%	$198.4474	$198.45	$198.45	$198.40
Purchase #2	$165.89	5.802%	$175.5149	$175.51	$175.50	$175.50
Purchase #3	$30.34	7.873%	$32.7287	$32.73	$32.75	$32.70
Purchase #4	$151.35	8.557%	$164.301	$164.30	$164.30	$164.30
Purchase #5	$164.66	7.783%	$177.4755	$177.48	$177.50	$177.50
Purchase #6	$94.54	5.336%	$99.5847	$99.58	$99.60	$99.60
Purchase #7	$203.71	11.333%	$226.7965	$226.80	$226.80	$226.80
7 purchase totals =	$1,002.26		$1,074.8487	$1,074.85	$1,074.90	$1,074.80