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	$56.31	9.553%	$61.6893	$61.69	$61.70	$61.70
Purchase #2	$94.79	7.393%	$101.7978	$101.80	$101.80	$101.80
Purchase #3	$48.68	6.621%	$51.9031	$51.90	$51.90	$51.90
Purchase #4	$244.77	11.735%	$273.4938	$273.49	$273.50	$273.50
Purchase #5	$238.67	12.503%	$268.5109	$268.51	$268.50	$268.50
Purchase #6	$148.73	8.528%	$161.4137	$161.41	$161.40	$161.40
Purchase #7	$92.57	8.179%	$100.1413	$100.14	$100.15	$100.10
7 purchase totals =	$924.52		$1,018.9499	$1,018.94	$1,018.95	$1,018.90