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	$176.96	12.738%	$199.5012	$199.50	$199.50	$199.50
Purchase #2	$28.51	7.624%	$30.6836	$30.68	$30.70	$30.70
Purchase #3	$40.71	4.782%	$42.6568	$42.66	$42.65	$42.70
Purchase #4	$184.85	6.235%	$196.3754	$196.38	$196.40	$196.40
Purchase #5	$158.96	7.835%	$171.4145	$171.41	$171.40	$171.40
Purchase #6	$128.81	9.595%	$141.1693	$141.17	$141.15	$141.20
Purchase #7	$225.51	7.860%	$243.2351	$243.24	$243.25	$243.20
7 purchase totals =	$944.31		$1,025.0359	$1,025.04	$1,025.05	$1,025.10