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	$187.54	3.293%	$193.7157	$193.72	$193.70	$193.70
Purchase #2	$45.39	6.784%	$48.4693	$48.47	$48.45	$48.50
Purchase #3	$137.86	5.246%	$145.0921	$145.09	$145.10	$145.10
Purchase #4	$145.58	12.818%	$164.2404	$164.24	$164.25	$164.20
Purchase #5	$48.37	7.332%	$51.9165	$51.92	$51.90	$51.90
Purchase #6	$147.60	7.223%	$158.2611	$158.26	$158.25	$158.30
Purchase #7	$250.53	5.220%	$263.6077	$263.61	$263.60	$263.60
7 purchase totals =	$962.87		$1,025.3028	$1,025.31	$1,025.25	$1,025.30