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	$193.51	4.751%	$202.7037	$202.70	$202.70	$202.70
Purchase #2	$121.58	4.659%	$127.2444	$127.24	$127.25	$127.20
Purchase #3	$141.96	12.622%	$159.8782	$159.88	$159.90	$159.90
Purchase #4	$142.69	11.162%	$158.6171	$158.62	$158.60	$158.60
Purchase #5	$134.95	9.161%	$147.3128	$147.31	$147.30	$147.30
Purchase #6	$174.51	6.223%	$185.3698	$185.37	$185.35	$185.40
Purchase #7	$69.55	3.771%	$72.1727	$72.17	$72.15	$72.20
7 purchase totals =	$978.75		$1,053.2987	$1,053.29	$1,053.25	$1,053.30