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	$179.53	7.214%	$192.4813	$192.48	$192.50	$192.50
Purchase #2	$139.52	7.291%	$149.6924	$149.69	$149.70	$149.70
Purchase #3	$15.30	7.151%	$16.3941	$16.39	$16.40	$16.40
Purchase #4	$210.33	5.479%	$221.854	$221.85	$221.85	$221.90
Purchase #5	$111.84	13.503%	$126.9418	$126.94	$126.95	$126.90
Purchase #6	$176.50	13.123%	$199.6621	$199.66	$199.65	$199.70
Purchase #7	$96.71	13.276%	$109.5492	$109.55	$109.55	$109.50
7 purchase totals =	$929.73		$1,016.5749	$1,016.56	$1,016.60	$1,016.60