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	$186.41	5.543%	$196.7427	$196.74	$196.75	$196.70
Purchase #2	$84.71	4.179%	$88.25	$88.25	$88.25	$88.30
Purchase #3	$8.61	12.734%	$9.7064	$9.71	$9.70	$9.70
Purchase #4	$119.85	4.383%	$125.103	$125.10	$125.10	$125.10
Purchase #5	$228.58	12.253%	$256.5879	$256.59	$256.60	$256.60
Purchase #6	$147.57	13.462%	$167.4359	$167.44	$167.45	$167.40
Purchase #7	$202.84	9.871%	$222.8623	$222.86	$222.85	$222.90
7 purchase totals =	$978.57		$1,066.6882	$1,066.69	$1,066.70	$1,066.70