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	$175.83	11.585%	$196.1999	$196.20	$196.20	$196.20
Purchase #2	$65.72	13.326%	$74.4778	$74.48	$74.50	$74.50
Purchase #3	$32.87	13.354%	$37.2595	$37.26	$37.25	$37.30
Purchase #4	$199.74	8.538%	$216.7938	$216.79	$216.80	$216.80
Purchase #5	$178.66	6.392%	$190.0799	$190.08	$190.10	$190.10
Purchase #6	$154.97	12.509%	$174.3552	$174.36	$174.35	$174.40
Purchase #7	$148.87	12.372%	$167.2882	$167.29	$167.30	$167.30
7 purchase totals =	$956.66		$1,056.4543	$1,056.46	$1,056.50	$1,056.60