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	$152.82	11.614%	$170.5685	$170.57	$170.55	$170.60
Purchase #2	$130.66	13.350%	$148.1031	$148.10	$148.10	$148.10
Purchase #3	$19.57	5.383%	$20.6235	$20.62	$20.60	$20.60
Purchase #4	$229.77	11.337%	$255.819	$255.82	$255.80	$255.80
Purchase #5	$244.95	9.639%	$268.5607	$268.56	$268.55	$268.60
Purchase #6	$147.46	13.217%	$166.9498	$166.95	$166.95	$166.90
Purchase #7	$24.43	4.767%	$25.5946	$25.59	$25.60	$25.60
7 purchase totals =	$949.66		$1,056.2192	$1,056.21	$1,056.15	$1,056.20