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	$208.41	5.301%	$219.4578	$219.46	$219.45	$219.50
Purchase #2	$58.50	4.424%	$61.088	$61.09	$61.10	$61.10
Purchase #3	$204.25	11.690%	$228.1268	$228.13	$228.15	$228.10
Purchase #4	$204.55	11.752%	$228.5887	$228.59	$228.60	$228.60
Purchase #5	$78.59	8.767%	$85.48	$85.48	$85.50	$85.50
Purchase #6	$207.94	11.775%	$232.4249	$232.42	$232.40	$232.40
Purchase #7	$184.31	13.726%	$209.6084	$209.61	$209.60	$209.60
7 purchase totals =	$1,146.55		$1,264.7746	$1,264.78	$1,264.80	$1,264.80