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	$94.97	11.560%	$105.9485	$105.95	$105.95	$105.90
Purchase #2	$192.53	9.740%	$211.2824	$211.28	$211.30	$211.30
Purchase #3	$205.35	9.471%	$224.7987	$224.80	$224.80	$224.80
Purchase #4	$135.75	11.396%	$151.2201	$151.22	$151.20	$151.20
Purchase #5	$162.41	6.165%	$172.4226	$172.42	$172.40	$172.40
Purchase #6	$99.62	4.277%	$103.8807	$103.88	$103.90	$103.90
Purchase #7	$70.50	9.834%	$77.433	$77.43	$77.45	$77.40
7 purchase totals =	$961.13		$1,046.9860	$1,046.98	$1,047.00	$1,046.90