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	$186.57	5.512%	$196.8537	$196.85	$196.85	$196.90
Purchase #2	$85.85	7.732%	$92.4879	$92.49	$92.50	$92.50
Purchase #3	$245.85	9.180%	$268.419	$268.42	$268.40	$268.40
Purchase #4	$57.50	4.859%	$60.2939	$60.29	$60.30	$60.30
Purchase #5	$220.97	12.137%	$247.7891	$247.79	$247.80	$247.80
Purchase #6	$126.85	11.516%	$141.458	$141.46	$141.45	$141.50
Purchase #7	$44.85	7.184%	$48.072	$48.07	$48.05	$48.10
7 purchase totals =	$968.44		$1,055.3736	$1,055.37	$1,055.35	$1,055.50