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	$92.84	3.341%	$95.9418	$95.94	$95.95	$95.90
Purchase #2	$77.29	11.281%	$86.0091	$86.01	$86.00	$86.00
Purchase #3	$246.80	6.607%	$263.1061	$263.11	$263.10	$263.10
Purchase #4	$40.98	3.741%	$42.5131	$42.51	$42.50	$42.50
Purchase #5	$90.54	3.151%	$93.3929	$93.39	$93.40	$93.40
Purchase #6	$50.51	8.317%	$54.7109	$54.71	$54.70	$54.70
Purchase #7	$72.73	4.847%	$76.2552	$76.26	$76.25	$76.30
7 purchase totals =	$671.69		$711.9291	$711.93	$711.90	$711.90