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	$208.61	5.205%	$219.4682	$219.47	$219.45	$219.50
Purchase #2	$71.32	10.258%	$78.636	$78.64	$78.65	$78.60
Purchase #3	$170.32	11.578%	$190.0396	$190.04	$190.05	$190.00
Purchase #4	$119.29	10.843%	$132.2246	$132.22	$132.20	$132.20
Purchase #5	$48.52	3.575%	$50.2546	$50.25	$50.25	$50.30
Purchase #6	$165.33	4.718%	$173.1303	$173.13	$173.15	$173.10
Purchase #7	$230.94	7.380%	$247.9834	$247.98	$248.00	$248.00
7 purchase totals =	$1,014.33		$1,091.7367	$1,091.73	$1,091.75	$1,091.70