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	$94.46	4.418%	$98.6332	$98.63	$98.65	$98.60
Purchase #2	$59.40	3.596%	$61.536	$61.54	$61.55	$61.50
Purchase #3	$239.77	4.329%	$250.1496	$250.15	$250.15	$250.10
Purchase #4	$197.84	8.329%	$214.3181	$214.32	$214.30	$214.30
Purchase #5	$179.77	3.139%	$185.413	$185.41	$185.40	$185.40
Purchase #6	$153.89	10.471%	$170.0038	$170.00	$170.00	$170.00
Purchase #7	$69.60	9.846%	$76.4528	$76.45	$76.45	$76.50
7 purchase totals =	$994.73		$1,056.5065	$1,056.50	$1,056.50	$1,056.40