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	$148.88	3.593%	$154.2293	$154.23	$154.25	$154.20
Purchase #2	$86.42	11.737%	$96.5631	$96.56	$96.55	$96.60
Purchase #3	$126.57	4.114%	$131.7771	$131.78	$131.80	$131.80
Purchase #4	$86.33	4.513%	$90.2261	$90.23	$90.25	$90.20
Purchase #5	$224.45	11.514%	$250.2932	$250.29	$250.30	$250.30
Purchase #6	$225.51	11.556%	$251.5699	$251.57	$251.55	$251.60
Purchase #7	$69.25	13.369%	$78.508	$78.51	$78.50	$78.50
7 purchase totals =	$967.41		$1,053.1667	$1,053.17	$1,053.20	$1,053.20