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	$187.94	4.403%	$196.215	$196.22	$196.20	$196.20
Purchase #2	$150.58	11.513%	$167.9163	$167.92	$167.90	$167.90
Purchase #3	$32.58	13.821%	$37.0829	$37.08	$37.10	$37.10
Purchase #4	$28.55	3.276%	$29.4853	$29.49	$29.50	$29.50
Purchase #5	$191.66	11.384%	$213.4786	$213.48	$213.50	$213.50
Purchase #6	$27.68	6.190%	$29.3934	$29.39	$29.40	$29.40
Purchase #7	$27.75	13.611%	$31.5271	$31.53	$31.55	$31.50
7 purchase totals =	$646.74		$705.0986	$705.11	$705.15	$705.10