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	$91.46	5.555%	$96.5406	$96.54	$96.55	$96.50
Purchase #2	$216.34	13.140%	$244.7671	$244.77	$244.75	$244.80
Purchase #3	$231.34	5.777%	$244.7045	$244.70	$244.70	$244.70
Purchase #4	$12.67	5.541%	$13.372	$13.37	$13.35	$13.40
Purchase #5	$137.35	12.851%	$155.0008	$155.00	$155.00	$155.00
Purchase #6	$59.89	9.834%	$65.7796	$65.78	$65.80	$65.80
Purchase #7	$188.60	5.594%	$199.1503	$199.15	$199.15	$199.20
7 purchase totals =	$937.65		$1,019.3149	$1,019.31	$1,019.30	$1,019.40