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	$209.37	6.716%	$223.4313	$223.43	$223.45	$223.40
Purchase #2	$170.46	8.847%	$185.5406	$185.54	$185.55	$185.50
Purchase #3	$139.90	6.812%	$149.43	$149.43	$149.45	$149.40
Purchase #4	$67.80	7.387%	$72.8084	$72.81	$72.80	$72.80
Purchase #5	$203.89	3.599%	$211.228	$211.23	$211.25	$211.20
Purchase #6	$39.45	8.370%	$42.752	$42.75	$42.75	$42.80
Purchase #7	$208.62	3.513%	$215.9488	$215.95	$215.95	$215.90
7 purchase totals =	$1,039.49		$1,101.1391	$1,101.14	$1,101.20	$1,101.00