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	$140.43	12.133%	$157.4684	$157.47	$157.45	$157.50
Purchase #2	$90.98	11.460%	$101.4063	$101.41	$101.40	$101.40
Purchase #3	$182.58	7.411%	$196.111	$196.11	$196.10	$196.10
Purchase #4	$203.91	11.840%	$228.0529	$228.05	$228.05	$228.10
Purchase #5	$7.63	11.805%	$8.5307	$8.53	$8.55	$8.50
Purchase #6	$155.92	10.774%	$172.7188	$172.72	$172.70	$172.70
Purchase #7	$179.82	5.654%	$189.987	$189.99	$190.00	$190.00
7 purchase totals =	$961.27		$1,054.2751	$1,054.28	$1,054.25	$1,054.30