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	$144.26	4.246%	$150.3853	$150.39	$150.40	$150.40
Purchase #2	$241.39	4.753%	$252.8633	$252.86	$252.85	$252.90
Purchase #3	$246.41	9.478%	$269.7647	$269.76	$269.75	$269.80
Purchase #4	$159.66	13.129%	$180.6218	$180.62	$180.60	$180.60
Purchase #5	$6.33	4.234%	$6.598	$6.60	$6.60	$6.60
Purchase #6	$95.29	4.787%	$99.8515	$99.85	$99.85	$99.90
Purchase #7	$50.80	4.565%	$53.119	$53.12	$53.10	$53.10
7 purchase totals =	$944.14		$1,013.2036	$1,013.20	$1,013.15	$1,013.30