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	$76.82	11.594%	$85.7265	$85.73	$85.75	$85.70
Purchase #2	$89.32	11.367%	$99.473	$99.47	$99.45	$99.50
Purchase #3	$187.61	11.596%	$209.3653	$209.37	$209.35	$209.40
Purchase #4	$49.27	3.546%	$51.0171	$51.02	$51.00	$51.00
Purchase #5	$206.31	5.812%	$218.3007	$218.30	$218.30	$218.30
Purchase #6	$176.96	13.441%	$200.7452	$200.75	$200.75	$200.70
Purchase #7	$175.98	4.146%	$183.2761	$183.28	$183.30	$183.30
7 purchase totals =	$962.27		$1,047.9039	$1,047.92	$1,047.90	$1,047.90