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	$207.45	7.251%	$222.4922	$222.49	$222.50	$222.50
Purchase #2	$198.65	7.555%	$213.658	$213.66	$213.65	$213.70
Purchase #3	$93.50	9.441%	$102.3273	$102.33	$102.35	$102.30
Purchase #4	$59.90	11.870%	$67.0101	$67.01	$67.00	$67.00
Purchase #5	$180.26	3.486%	$186.5439	$186.54	$186.55	$186.50
Purchase #6	$110.34	7.828%	$118.9774	$118.98	$119.00	$119.00
Purchase #7	$147.29	3.463%	$152.3907	$152.39	$152.40	$152.40
7 purchase totals =	$997.39		$1,063.3996	$1,063.40	$1,063.45	$1,063.40