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	$69.52	4.216%	$72.451	$72.45	$72.45	$72.50
Purchase #2	$234.75	3.726%	$243.4968	$243.50	$243.50	$243.50
Purchase #3	$157.54	3.242%	$162.6474	$162.65	$162.65	$162.60
Purchase #4	$216.93	13.725%	$246.7036	$246.70	$246.70	$246.70
Purchase #5	$111.47	12.151%	$125.0147	$125.01	$125.00	$125.00
Purchase #6	$48.92	12.743%	$55.1539	$55.15	$55.15	$55.20
Purchase #7	$40.73	11.474%	$45.4034	$45.40	$45.40	$45.40
7 purchase totals =	$879.86		$950.8708	$950.86	$950.85	$950.90