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	$175.76	11.632%	$196.2044	$196.20	$196.20	$196.20
Purchase #2	$157.27	8.823%	$171.1459	$171.15	$171.15	$171.10
Purchase #3	$31.32	5.803%	$33.1375	$33.14	$33.15	$33.10
Purchase #4	$19.96	8.109%	$21.5786	$21.58	$21.60	$21.60
Purchase #5	$193.83	9.567%	$212.3737	$212.37	$212.35	$212.40
Purchase #6	$173.59	5.379%	$182.9274	$182.93	$182.95	$182.90
Purchase #7	$178.96	8.496%	$194.1644	$194.16	$194.15	$194.20
7 purchase totals =	$930.69		$1,011.5319	$1,011.53	$1,011.55	$1,011.50