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	$88.39	9.671%	$96.9382	$96.94	$96.95	$96.90
Purchase #2	$157.79	4.425%	$164.7722	$164.77	$164.75	$164.80
Purchase #3	$171.62	10.657%	$189.9095	$189.91	$189.90	$189.90
Purchase #4	$90.39	10.601%	$99.9722	$99.97	$99.95	$100.00
Purchase #5	$188.34	5.197%	$198.128	$198.13	$198.15	$198.10
Purchase #6	$157.77	10.461%	$174.2743	$174.27	$174.25	$174.30
Purchase #7	$210.59	6.822%	$224.9564	$224.96	$224.95	$225.00
7 purchase totals =	$1,064.89		$1,148.9508	$1,148.95	$1,148.90	$1,149.00