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	$162.47	7.689%	$174.9623	$174.96	$174.95	$175.00
Purchase #2	$115.76	13.640%	$131.5497	$131.55	$131.55	$131.50
Purchase #3	$18.90	8.735%	$20.5509	$20.55	$20.55	$20.60
Purchase #4	$235.62	6.726%	$251.4678	$251.47	$251.45	$251.50
Purchase #5	$161.33	5.656%	$170.4548	$170.45	$170.45	$170.50
Purchase #6	$90.65	6.819%	$96.8314	$96.83	$96.85	$96.80
Purchase #7	$243.54	12.313%	$273.5271	$273.53	$273.55	$273.50
7 purchase totals =	$1,028.27		$1,119.3440	$1,119.34	$1,119.35	$1,119.40