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	$157.42	10.534%	$174.0026	$174.00	$174.00	$174.00
Purchase #2	$39.58	3.155%	$40.8287	$40.83	$40.85	$40.80
Purchase #3	$59.65	12.696%	$67.2232	$67.22	$67.20	$67.20
Purchase #4	$155.57	7.594%	$167.384	$167.38	$167.40	$167.40
Purchase #5	$166.72	9.858%	$183.1553	$183.16	$183.15	$183.20
Purchase #6	$245.92	5.206%	$258.7226	$258.72	$258.70	$258.70
Purchase #7	$157.95	10.474%	$174.4937	$174.49	$174.50	$174.50
7 purchase totals =	$982.81		$1,065.8101	$1,065.80	$1,065.80	$1,065.80