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	$132.82	13.701%	$151.0177	$151.02	$151.00	$151.00
Purchase #2	$229.48	11.329%	$255.4778	$255.48	$255.50	$255.50
Purchase #3	$172.33	11.195%	$191.6223	$191.62	$191.60	$191.60
Purchase #4	$242.40	11.108%	$269.3258	$269.33	$269.35	$269.30
Purchase #5	$209.39	9.269%	$228.7984	$228.80	$228.80	$228.80
Purchase #6	$119.28	10.286%	$131.5491	$131.55	$131.55	$131.50
Purchase #7	$228.58	11.738%	$255.4107	$255.41	$255.40	$255.40
7 purchase totals =	$1,334.28		$1,483.2018	$1,483.21	$1,483.20	$1,483.10