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	$147.56	5.783%	$156.0934	$156.09	$156.10	$156.10
Purchase #2	$216.81	9.350%	$237.0817	$237.08	$237.10	$237.10
Purchase #3	$209.77	4.613%	$219.4467	$219.45	$219.45	$219.40
Purchase #4	$175.84	10.631%	$194.5336	$194.53	$194.55	$194.50
Purchase #5	$118.73	9.686%	$130.2302	$130.23	$130.25	$130.20
Purchase #6	$200.40	7.283%	$214.9951	$215.00	$215.00	$215.00
Purchase #7	$42.32	3.848%	$43.9485	$43.95	$43.95	$43.90
7 purchase totals =	$1,111.43		$1,196.3292	$1,196.33	$1,196.40	$1,196.20