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	$207.63	5.807%	$219.6871	$219.69	$219.70	$219.70
Purchase #2	$92.88	13.710%	$105.6138	$105.61	$105.60	$105.60
Purchase #3	$114.48	12.334%	$128.6	$128.60	$128.60	$128.60
Purchase #4	$130.97	12.819%	$147.759	$147.76	$147.75	$147.80
Purchase #5	$98.93	13.363%	$112.15	$112.15	$112.15	$112.20
Purchase #6	$199.58	9.164%	$217.8695	$217.87	$217.85	$217.90
Purchase #7	$223.41	13.349%	$253.233	$253.23	$253.25	$253.20
7 purchase totals =	$1,067.88		$1,184.9124	$1,184.91	$1,184.90	$1,185.00