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	$206.61	10.767%	$228.8557	$228.86	$228.85	$228.90
Purchase #2	$141.54	7.700%	$152.4386	$152.44	$152.45	$152.40
Purchase #3	$104.63	6.718%	$111.659	$111.66	$111.65	$111.70
Purchase #4	$33.57	12.624%	$37.8079	$37.81	$37.80	$37.80
Purchase #5	$103.81	8.501%	$112.6349	$112.63	$112.65	$112.60
Purchase #6	$205.77	3.265%	$212.4884	$212.49	$212.50	$212.50
Purchase #7	$154.92	7.556%	$166.6258	$166.63	$166.65	$166.60
7 purchase totals =	$950.85		$1,022.5103	$1,022.52	$1,022.55	$1,022.50