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	$103.89	4.388%	$108.4487	$108.45	$108.45	$108.40
Purchase #2	$140.51	11.274%	$156.3511	$156.35	$156.35	$156.40
Purchase #3	$192.64	12.388%	$216.5042	$216.50	$216.50	$216.50
Purchase #4	$73.25	6.843%	$78.2625	$78.26	$78.25	$78.30
Purchase #5	$197.40	9.383%	$215.922	$215.92	$215.90	$215.90
Purchase #6	$207.44	3.843%	$215.4119	$215.41	$215.40	$215.40
Purchase #7	$60.51	3.498%	$62.6266	$62.63	$62.65	$62.60
7 purchase totals =	$975.64		$1,053.5270	$1,053.52	$1,053.50	$1,053.50