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	$78.61	4.810%	$82.3911	$82.39	$82.40	$82.40
Purchase #2	$56.57	8.283%	$61.2557	$61.26	$61.25	$61.30
Purchase #3	$198.33	11.619%	$221.374	$221.37	$221.35	$221.40
Purchase #4	$235.72	4.130%	$245.4552	$245.46	$245.45	$245.50
Purchase #5	$19.51	12.489%	$21.9466	$21.95	$21.95	$21.90
Purchase #6	$167.48	3.252%	$172.9264	$172.93	$172.95	$172.90
Purchase #7	$194.95	11.403%	$217.1801	$217.18	$217.20	$217.20
7 purchase totals =	$951.17		$1,022.5291	$1,022.54	$1,022.55	$1,022.60