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	$58.38	4.605%	$61.0684	$61.07	$61.05	$61.10
Purchase #2	$221.71	8.553%	$240.6729	$240.67	$240.65	$240.70
Purchase #3	$208.71	6.538%	$222.3555	$222.36	$222.35	$222.40
Purchase #4	$76.45	11.811%	$85.4795	$85.48	$85.50	$85.50
Purchase #5	$179.99	8.704%	$195.6563	$195.66	$195.65	$195.70
Purchase #6	$88.47	8.548%	$96.0324	$96.03	$96.05	$96.00
Purchase #7	$119.45	3.740%	$123.9174	$123.92	$123.90	$123.90
7 purchase totals =	$953.16		$1,025.1824	$1,025.19	$1,025.15	$1,025.30