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	$213.53	9.753%	$234.3556	$234.36	$234.35	$234.40
Purchase #2	$224.34	4.133%	$233.612	$233.61	$233.60	$233.60
Purchase #3	$35.71	5.189%	$37.563	$37.56	$37.55	$37.60
Purchase #4	$215.69	5.344%	$227.2165	$227.22	$227.20	$227.20
Purchase #5	$54.73	10.146%	$60.2829	$60.28	$60.30	$60.30
Purchase #6	$130.76	11.817%	$146.2119	$146.21	$146.20	$146.20
Purchase #7	$130.81	7.240%	$140.2806	$140.28	$140.30	$140.30
7 purchase totals =	$1,005.57		$1,079.5225	$1,079.52	$1,079.50	$1,079.60