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	$86.64	10.374%	$95.628	$95.63	$95.65	$95.60
Purchase #2	$71.36	9.315%	$78.0072	$78.01	$78.00	$78.00
Purchase #3	$50.67	11.472%	$56.4829	$56.48	$56.50	$56.50
Purchase #4	$68.64	3.617%	$71.1227	$71.12	$71.10	$71.10
Purchase #5	$100.97	5.517%	$106.5405	$106.54	$106.55	$106.50
Purchase #6	$228.59	6.337%	$243.0757	$243.08	$243.10	$243.10
Purchase #7	$63.57	12.321%	$71.4025	$71.40	$71.40	$71.40
7 purchase totals =	$670.44		$722.2595	$722.26	$722.30	$722.20