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	$112.95	5.676%	$119.361	$119.36	$119.35	$119.40
Purchase #2	$199.45	11.766%	$222.9173	$222.92	$222.90	$222.90
Purchase #3	$73.49	6.352%	$78.1581	$78.16	$78.15	$78.20
Purchase #4	$217.32	5.437%	$229.1357	$229.14	$229.15	$229.10
Purchase #5	$67.93	7.125%	$72.77	$72.77	$72.75	$72.80
Purchase #6	$141.43	5.686%	$149.4717	$149.47	$149.45	$149.50
Purchase #7	$176.39	10.381%	$194.701	$194.70	$194.70	$194.70
7 purchase totals =	$988.96		$1,066.5148	$1,066.52	$1,066.45	$1,066.60