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	$189.76	6.829%	$202.7187	$202.72	$202.70	$202.70
Purchase #2	$205.42	9.333%	$224.5918	$224.59	$224.60	$224.60
Purchase #3	$110.49	11.616%	$123.3245	$123.32	$123.30	$123.30
Purchase #4	$144.58	12.353%	$162.44	$162.44	$162.45	$162.40
Purchase #5	$196.57	8.567%	$213.4102	$213.41	$213.40	$213.40
Purchase #6	$52.29	5.810%	$55.328	$55.33	$55.35	$55.30
Purchase #7	$47.72	6.217%	$50.6868	$50.69	$50.70	$50.70
7 purchase totals =	$946.83		$1,032.5000	$1,032.50	$1,032.50	$1,032.40