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	$195.90	11.462%	$218.3541	$218.35	$218.35	$218.40
Purchase #2	$6.77	13.322%	$7.6719	$7.67	$7.65	$7.70
Purchase #3	$89.31	12.573%	$100.5389	$100.54	$100.55	$100.50
Purchase #4	$35.41	9.279%	$38.6957	$38.70	$38.70	$38.70
Purchase #5	$172.47	10.733%	$190.9812	$190.98	$191.00	$191.00
Purchase #6	$195.97	11.719%	$218.9357	$218.94	$218.95	$218.90
Purchase #7	$123.38	6.427%	$131.3096	$131.31	$131.30	$131.30
7 purchase totals =	$819.21		$906.4871	$906.49	$906.50	$906.50