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	$100.61	4.825%	$105.4644	$105.46	$105.45	$105.50
Purchase #2	$87.52	4.113%	$91.1197	$91.12	$91.10	$91.10
Purchase #3	$50.93	4.771%	$53.3599	$53.36	$53.35	$53.40
Purchase #4	$194.89	8.790%	$212.0208	$212.02	$212.00	$212.00
Purchase #5	$40.88	3.473%	$42.2998	$42.30	$42.30	$42.30
Purchase #6	$73.77	3.824%	$76.591	$76.59	$76.60	$76.60
Purchase #7	$145.37	8.699%	$158.0157	$158.02	$158.00	$158.00
7 purchase totals =	$693.97		$738.8713	$738.87	$738.80	$738.90