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	$164.25	6.567%	$175.0363	$175.04	$175.05	$175.00
Purchase #2	$191.60	4.620%	$200.4519	$200.45	$200.45	$200.50
Purchase #3	$103.51	11.141%	$115.042	$115.04	$115.05	$115.00
Purchase #4	$81.29	11.467%	$90.6115	$90.61	$90.60	$90.60
Purchase #5	$179.86	4.839%	$188.5634	$188.56	$188.55	$188.60
Purchase #6	$122.30	5.520%	$129.051	$129.05	$129.05	$129.10
Purchase #7	$163.48	10.639%	$180.8726	$180.87	$180.85	$180.90
7 purchase totals =	$1,006.29		$1,079.6287	$1,079.62	$1,079.60	$1,079.70