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	$183.86	11.796%	$205.5481	$205.55	$205.55	$205.50
Purchase #2	$155.82	7.558%	$167.5969	$167.60	$167.60	$167.60
Purchase #3	$43.59	3.801%	$45.2469	$45.25	$45.25	$45.20
Purchase #4	$207.97	5.275%	$218.9404	$218.94	$218.95	$218.90
Purchase #5	$119.85	13.839%	$136.436	$136.44	$136.45	$136.40
Purchase #6	$96.99	8.495%	$105.2293	$105.23	$105.25	$105.20
Purchase #7	$168.67	8.556%	$183.1014	$183.10	$183.10	$183.10
7 purchase totals =	$976.75		$1,062.0990	$1,062.11	$1,062.15	$1,061.90