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	$213.58	4.848%	$223.9344	$223.93	$223.95	$223.90
Purchase #2	$91.79	7.427%	$98.6072	$98.61	$98.60	$98.60
Purchase #3	$141.45	12.307%	$158.8583	$158.86	$158.85	$158.90
Purchase #4	$76.35	11.805%	$85.3631	$85.36	$85.35	$85.40
Purchase #5	$175.85	4.792%	$184.2767	$184.28	$184.30	$184.30
Purchase #6	$141.96	5.669%	$150.0077	$150.01	$150.00	$150.00
Purchase #7	$206.40	5.826%	$218.4249	$218.42	$218.40	$218.40
7 purchase totals =	$1,047.38		$1,119.4723	$1,119.47	$1,119.45	$1,119.50