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	$193.32	7.779%	$208.3584	$208.36	$208.35	$208.40
Purchase #2	$184.59	6.374%	$196.3558	$196.36	$196.35	$196.40
Purchase #3	$248.46	5.132%	$261.211	$261.21	$261.20	$261.20
Purchase #4	$117.84	4.859%	$123.5658	$123.57	$123.55	$123.60
Purchase #5	$16.47	11.200%	$18.3146	$18.31	$18.30	$18.30
Purchase #6	$176.51	5.699%	$186.5693	$186.57	$186.55	$186.60
Purchase #7	$142.58	7.228%	$152.8857	$152.89	$152.90	$152.90
7 purchase totals =	$1,079.77		$1,147.2606	$1,147.27	$1,147.20	$1,147.40