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	$216.30	11.240%	$240.6121	$240.61	$240.60	$240.60
Purchase #2	$201.33	7.176%	$215.7774	$215.78	$215.80	$215.80
Purchase #3	$243.63	13.616%	$276.8027	$276.80	$276.80	$276.80
Purchase #4	$197.90	10.457%	$218.5944	$218.59	$218.60	$218.60
Purchase #5	$33.94	9.408%	$37.1331	$37.13	$37.15	$37.10
Purchase #6	$43.30	11.795%	$48.4072	$48.41	$48.40	$48.40
Purchase #7	$35.59	4.743%	$37.278	$37.28	$37.30	$37.30
7 purchase totals =	$971.99		$1,074.6049	$1,074.60	$1,074.65	$1,074.60