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	$102.56	8.205%	$110.975	$110.98	$111.00	$111.00
Purchase #2	$175.88	13.473%	$199.5763	$199.58	$199.60	$199.60
Purchase #3	$43.39	13.322%	$49.1704	$49.17	$49.15	$49.20
Purchase #4	$183.70	13.805%	$209.0598	$209.06	$209.05	$209.10
Purchase #5	$89.26	11.236%	$99.2893	$99.29	$99.30	$99.30
Purchase #6	$215.41	3.511%	$222.973	$222.97	$222.95	$223.00
Purchase #7	$184.95	6.139%	$196.3041	$196.30	$196.30	$196.30
7 purchase totals =	$995.15		$1,087.3479	$1,087.35	$1,087.35	$1,087.50