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	$54.93	11.380%	$61.181	$61.18	$61.20	$61.20
Purchase #2	$112.34	11.601%	$125.3726	$125.37	$125.35	$125.40
Purchase #3	$32.78	13.790%	$37.3004	$37.30	$37.30	$37.30
Purchase #4	$26.26	3.274%	$27.1198	$27.12	$27.10	$27.10
Purchase #5	$63.34	6.229%	$67.2854	$67.29	$67.30	$67.30
Purchase #6	$182.90	13.334%	$207.2879	$207.29	$207.30	$207.30
Purchase #7	$57.46	7.189%	$61.5908	$61.59	$61.60	$61.60
7 purchase totals =	$530.01		$587.1379	$587.14	$587.15	$587.20