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	$219.63	6.193%	$233.2317	$233.23	$233.25	$233.20
Purchase #2	$30.36	10.392%	$33.515	$33.52	$33.50	$33.50
Purchase #3	$38.99	9.525%	$42.7038	$42.70	$42.70	$42.70
Purchase #4	$70.66	10.835%	$78.316	$78.32	$78.30	$78.30
Purchase #5	$112.41	5.235%	$118.2947	$118.29	$118.30	$118.30
Purchase #6	$28.60	8.524%	$31.0379	$31.04	$31.05	$31.00
Purchase #7	$224.73	10.560%	$248.4615	$248.46	$248.45	$248.50
7 purchase totals =	$725.38		$785.5606	$785.56	$785.55	$785.50