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	$221.47	11.747%	$247.4861	$247.49	$247.50	$247.50
Purchase #2	$71.60	9.648%	$78.508	$78.51	$78.50	$78.50
Purchase #3	$73.28	5.820%	$77.5449	$77.54	$77.55	$77.50
Purchase #4	$116.36	6.471%	$123.8897	$123.89	$123.90	$123.90
Purchase #5	$150.46	4.350%	$157.005	$157.01	$157.00	$157.00
Purchase #6	$157.67	13.533%	$179.0075	$179.01	$179.00	$179.00
Purchase #7	$235.25	5.519%	$248.2334	$248.23	$248.25	$248.20
7 purchase totals =	$1,026.09		$1,111.6746	$1,111.68	$1,111.70	$1,111.60