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	$213.31	11.644%	$238.1478	$238.15	$238.15	$238.10
Purchase #2	$205.62	3.124%	$212.0436	$212.04	$212.05	$212.00
Purchase #3	$184.40	9.614%	$202.1282	$202.13	$202.15	$202.10
Purchase #4	$97.71	8.209%	$105.731	$105.73	$105.75	$105.70
Purchase #5	$86.32	5.820%	$91.3438	$91.34	$91.35	$91.30
Purchase #6	$132.30	9.134%	$144.3843	$144.38	$144.40	$144.40
Purchase #7	$105.42	5.314%	$111.022	$111.02	$111.00	$111.00
7 purchase totals =	$1,025.08		$1,104.8007	$1,104.79	$1,104.85	$1,104.60