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	$217.54	4.419%	$227.1531	$227.15	$227.15	$227.20
Purchase #2	$6.99	7.662%	$7.5256	$7.53	$7.55	$7.50
Purchase #3	$75.28	9.164%	$82.1787	$82.18	$82.20	$82.20
Purchase #4	$200.90	4.358%	$209.6552	$209.66	$209.65	$209.70
Purchase #5	$67.92	7.312%	$72.8863	$72.89	$72.90	$72.90
Purchase #6	$120.95	8.329%	$131.0239	$131.02	$131.00	$131.00
Purchase #7	$71.25	8.751%	$77.4851	$77.49	$77.50	$77.50
7 purchase totals =	$760.83		$807.9079	$807.92	$807.95	$808.00