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	$201.94	5.443%	$212.9316	$212.93	$212.95	$212.90
Purchase #2	$48.63	11.119%	$54.0372	$54.04	$54.05	$54.00
Purchase #3	$55.70	8.498%	$60.4334	$60.43	$60.45	$60.40
Purchase #4	$71.37	10.272%	$78.7011	$78.70	$78.70	$78.70
Purchase #5	$83.39	7.334%	$89.5058	$89.51	$89.50	$89.50
Purchase #6	$122.56	3.399%	$126.7258	$126.73	$126.75	$126.70
Purchase #7	$172.80	4.425%	$180.4464	$180.45	$180.45	$180.40
7 purchase totals =	$756.39		$802.7813	$802.79	$802.85	$802.60