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	$178.73	9.831%	$196.3009	$196.30	$196.30	$196.30
Purchase #2	$119.53	9.248%	$130.5841	$130.58	$130.60	$130.60
Purchase #3	$26.60	3.853%	$27.6249	$27.62	$27.60	$27.60
Purchase #4	$93.72	6.282%	$99.6075	$99.61	$99.60	$99.60
Purchase #5	$238.28	5.248%	$250.7849	$250.78	$250.80	$250.80
Purchase #6	$176.88	3.203%	$182.5455	$182.55	$182.55	$182.50
Purchase #7	$116.85	12.569%	$131.5369	$131.54	$131.55	$131.50
7 purchase totals =	$950.59		$1,018.9847	$1,018.98	$1,019.00	$1,018.90