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	$196.95	7.373%	$211.4711	$211.47	$211.45	$211.50
Purchase #2	$150.43	11.208%	$167.2902	$167.29	$167.30	$167.30
Purchase #3	$108.76	12.390%	$122.2354	$122.24	$122.25	$122.20
Purchase #4	$31.67	5.281%	$33.3425	$33.34	$33.35	$33.30
Purchase #5	$212.77	9.722%	$233.4555	$233.46	$233.45	$233.50
Purchase #6	$199.89	11.131%	$222.1398	$222.14	$222.15	$222.10
Purchase #7	$45.86	5.541%	$48.4011	$48.40	$48.40	$48.40
7 purchase totals =	$946.33		$1,038.3356	$1,038.34	$1,038.35	$1,038.30