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	$118.52	5.764%	$125.3515	$125.35	$125.35	$125.40
Purchase #2	$198.67	5.504%	$209.6048	$209.60	$209.60	$209.60
Purchase #3	$90.85	6.107%	$96.3982	$96.40	$96.40	$96.40
Purchase #4	$232.41	6.271%	$246.9844	$246.98	$247.00	$247.00
Purchase #5	$117.50	4.802%	$123.1424	$123.14	$123.15	$123.10
Purchase #6	$54.78	10.646%	$60.6119	$60.61	$60.60	$60.60
Purchase #7	$79.52	3.621%	$82.3994	$82.40	$82.40	$82.40
7 purchase totals =	$892.25		$944.4926	$944.48	$944.50	$944.50