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	$192.34	4.165%	$200.351	$200.35	$200.35	$200.40
Purchase #2	$67.42	8.128%	$72.8999	$72.90	$72.90	$72.90
Purchase #3	$211.92	12.780%	$239.0034	$239.00	$239.00	$239.00
Purchase #4	$36.92	11.544%	$41.182	$41.18	$41.20	$41.20
Purchase #5	$6.98	7.272%	$7.4876	$7.49	$7.50	$7.50
Purchase #6	$72.25	12.850%	$81.5341	$81.53	$81.55	$81.50
Purchase #7	$78.47	5.198%	$82.5489	$82.55	$82.55	$82.50
7 purchase totals =	$666.30		$725.0069	$725.00	$725.05	$725.00