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	$152.87	7.512%	$164.3536	$164.35	$164.35	$164.40
Purchase #2	$244.75	11.687%	$273.3539	$273.35	$273.35	$273.40
Purchase #3	$40.86	3.343%	$42.2259	$42.23	$42.25	$42.20
Purchase #4	$95.25	7.180%	$102.089	$102.09	$102.10	$102.10
Purchase #5	$73.44	11.291%	$81.7321	$81.73	$81.75	$81.70
Purchase #6	$230.74	11.832%	$258.0412	$258.04	$258.05	$258.00
Purchase #7	$154.61	6.619%	$164.8436	$164.84	$164.85	$164.80
7 purchase totals =	$992.52		$1,086.6393	$1,086.63	$1,086.70	$1,086.60