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	$97.52	7.506%	$104.8399	$104.84	$104.85	$104.80
Purchase #2	$85.53	8.659%	$92.936	$92.94	$92.95	$92.90
Purchase #3	$36.54	3.725%	$37.9011	$37.90	$37.90	$37.90
Purchase #4	$235.50	7.480%	$253.1154	$253.12	$253.10	$253.10
Purchase #5	$46.37	3.780%	$48.1228	$48.12	$48.10	$48.10
Purchase #6	$113.67	3.204%	$117.312	$117.31	$117.30	$117.30
Purchase #7	$70.51	3.113%	$72.705	$72.71	$72.70	$72.70
7 purchase totals =	$685.64		$726.9322	$726.94	$726.90	$726.80