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	$195.95	13.568%	$222.5365	$222.54	$222.55	$222.50
Purchase #2	$241.80	7.487%	$259.9036	$259.90	$259.90	$259.90
Purchase #3	$40.65	10.711%	$45.004	$45.00	$45.00	$45.00
Purchase #4	$153.95	10.259%	$169.7437	$169.74	$169.75	$169.70
Purchase #5	$85.58	12.862%	$96.5873	$96.59	$96.60	$96.60
Purchase #6	$32.66	3.743%	$33.8825	$33.88	$33.90	$33.90
Purchase #7	$186.35	13.484%	$211.4774	$211.48	$211.50	$211.50
7 purchase totals =	$936.94		$1,039.1350	$1,039.13	$1,039.20	$1,039.10