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	$191.28	7.357%	$205.3525	$205.35	$205.35	$205.40
Purchase #2	$190.48	8.746%	$207.1394	$207.14	$207.15	$207.10
Purchase #3	$70.90	11.124%	$78.7869	$78.79	$78.80	$78.80
Purchase #4	$174.41	12.462%	$196.145	$196.15	$196.15	$196.10
Purchase #5	$102.25	13.824%	$116.385	$116.39	$116.40	$116.40
Purchase #6	$249.51	7.695%	$268.7098	$268.71	$268.70	$268.70
Purchase #7	$206.27	4.193%	$214.9189	$214.92	$214.90	$214.90
7 purchase totals =	$1,185.10		$1,287.4375	$1,287.45	$1,287.45	$1,287.40