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	$58.77	3.340%	$60.7329	$60.73	$60.75	$60.70
Purchase #2	$20.82	3.648%	$21.5795	$21.58	$21.60	$21.60
Purchase #3	$103.35	3.543%	$107.0117	$107.01	$107.00	$107.00
Purchase #4	$226.41	3.154%	$233.551	$233.55	$233.55	$233.60
Purchase #5	$41.57	4.549%	$43.461	$43.46	$43.45	$43.50
Purchase #6	$167.58	10.600%	$185.3435	$185.34	$185.35	$185.30
Purchase #7	$109.87	8.208%	$118.8881	$118.89	$118.90	$118.90
7 purchase totals =	$728.37		$770.5677	$770.56	$770.60	$770.60