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	$250.26	9.453%	$273.9171	$273.92	$273.90	$273.90
Purchase #2	$199.52	11.432%	$222.3291	$222.33	$222.35	$222.30
Purchase #3	$5.92	4.687%	$6.1975	$6.20	$6.20	$6.20
Purchase #4	$220.93	4.709%	$231.3336	$231.33	$231.35	$231.30
Purchase #5	$192.60	4.158%	$200.6083	$200.61	$200.60	$200.60
Purchase #6	$90.89	5.105%	$95.5299	$95.53	$95.55	$95.50
Purchase #7	$84.43	13.844%	$96.1185	$96.12	$96.10	$96.10
7 purchase totals =	$1,044.55		$1,126.0340	$1,126.04	$1,126.05	$1,125.90