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	$182.98	7.295%	$196.3284	$196.33	$196.35	$196.30
Purchase #2	$152.39	12.463%	$171.3824	$171.38	$171.40	$171.40
Purchase #3	$45.35	3.852%	$47.0969	$47.10	$47.10	$47.10
Purchase #4	$152.98	10.661%	$169.2892	$169.29	$169.30	$169.30
Purchase #5	$92.68	3.580%	$95.9979	$96.00	$96.00	$96.00
Purchase #6	$81.55	6.582%	$86.9176	$86.92	$86.90	$86.90
Purchase #7	$28.63	4.448%	$29.9035	$29.90	$29.90	$29.90
7 purchase totals =	$736.56		$796.9159	$796.92	$796.95	$796.90