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	$209.29	10.527%	$231.322	$231.32	$231.30	$231.30
Purchase #2	$42.65	4.522%	$44.5786	$44.58	$44.60	$44.60
Purchase #3	$113.73	11.380%	$126.6725	$126.67	$126.65	$126.70
Purchase #4	$168.36	6.640%	$179.5391	$179.54	$179.55	$179.50
Purchase #5	$183.74	7.185%	$196.9417	$196.94	$196.95	$196.90
Purchase #6	$198.59	6.497%	$211.4924	$211.49	$211.50	$211.50
Purchase #7	$220.61	13.574%	$250.5556	$250.56	$250.55	$250.60
7 purchase totals =	$1,136.97		$1,241.1019	$1,241.10	$1,241.10	$1,241.10